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United States Air Force 
Scientific Advisory Board 




Report on 

Aircraft Oxygen Generation 



SAB-TR-11-04 
1 February 2012 



DISTRIBUTION AUTHORIZED 

In accordance with AFI 61-204 and DODD 
5230.24, Distribution Statement A, Approved 
for Public Release, Distribution Unlimited. 



This report is a product of the United States Air Force Scientific Advisory Board 2011 
Quicklook Study on Aircraft Oxygen Generation. Statements, opinions, recommendations, 
and conclusions contained in this report are those of the Study members and do not 
necessarily represent the official position of the United States Air Force or the Department 
of Defense. 



United States Air Force 
Scientific Advisory Board 




Report on 

Aircraft Oxygen Generation 



SAB-TR-1 1 -04 
1 February 2012 



(This Page Intentionally Left Blank) 



a 



Foreword 



Many aircraft make use of an on-board oxygen generation system to provide breathing 
oxygen for the aircrew. Compared to historical experience, there have been an increasing 
number of hypoxia-like incidents in the F-22 Raptor aircraft, that may be related to their 
on-board oxygen generating systems (OBOGS) or their installation. 

The United States Air Force (USAF) Scientific Advisory Board was tasked to conduct a 
Quicklook Study of system safety issues involving OBOGS to help ensure that the appropriate 
steps are being taken to enhance flight safety of these aircraft. These included, but were not 
limited to, evaluating the current F-22 oxygen system, evaluating OBOGS and life support 
systems in general, investigating contaminants that could have an effect on OBOGS operation, 
evaluating human responses to high altitude rapid cabin altitude changes/rapid decompression 
environment with less that 90% oxygen, assisting with F-22 return-to-fly criteria as requested, 
revalidating and clarifying Air Standards, reviewing and validating implementation of 
performance-based acquisition programs and associated risk analysis protocols, examining 
specific hypoxia-like incidents occurring in flight regimes not normally considered likely for 
hypoxia events, and reviewing and revalidating all aircrew flight equipment affiliated with 
OBOGS-equipped aircraft. Priority was given to F-22 aircraft; however, other 
OBOGS-equipped aircraft were also considered. 

The Aircraft Oxygen Generation (AOG) Study Panel members included those with a 
broad technical, acquisition/research, operational, and medical background, and included 
members from Industry and Academia, as well as retired military members with relevant 
experience. Also, the Panel received numerous inputs from the USAF Safety Center's safety 
investigation board members well as the F-22 Combined Test Force and the F-22 System 
Program Office. 

The undersigned also wish to acknowledge the outstanding effort and support received 
from the members of the entire Study Panel, the General Officer and Senior Executive Service 
participants, the Air Force Safety Center and the safety investigation board members, the invited 
USAF, US Navy, and contractor subject matter experts, the Study Executive Officers, and the 
Scientific Advisory Board Secretariat staff. 




AOG Study Chair 



AOG Study Vice Chair 



Hi 



Note in Proof 

After completion of the Aircraft Oxygen Generation (AOG) Quicklook 
Study the AOG Study Panel was made aware that the F-22 Life Support Systems 
Task Force has continued the testing and analysis recommended by the Study Panel 
and has determined what they believe to be a root cause. As this report was going to 
print, there are recent indications that the operation and interaction of the Breathing 
Regulator Anti-G valve and the pilot's life support equipment can, under certain 
conditions, cause a restriction to the pilot's normal breathing process. The Study 
Panel was recently briefed on the Task Force's findings and considers it appropriate 
to acknowledge this new information in order to place the contents of this Final 
Report of the Air Force Scientific Advisory Board's Aircraft Oxygen Generation 
Study in proper context. 



iv 



Executive Summary 



Introduction 

Airborne Oxygen Generation (AOG) Systems are used on most fighter aircraft due to 
reduced servicing and logistics support, and safety considerations. The F-22 aircraft is equipped 
with such a system to provide breathing air to the pilot. This system takes engine bleed air and 
concentrates it to the appropriate partial pressure of oxygen as determined by the cabin altitude. 

Beginning in 2008, the F-22 aircraft began to experience a significantly higher rate of 
hypoxia-like incidents with unknown causes as reported by the pilots. The Air Force was not 
able to determine the "root cause" for these incidents and a further review was recommended to 
the Secretary of the Air Force. The Secretary then tasked the United States Air Force (USAF) 
Scientific Advisory Board (SAB) to perform a Quicklook Study to cover three areas: 

1. Continue the ongoing efforts to determine root cause(s), to include: Gathering data 
during dynamic, in-flight testing; full reviews of both the life support equipment and the 
aircraft's potential for passing contaminants into the cockpit and/or breathing air; and 
finally, to better understand the similarities and differences between the F-22 oxygen 
generating system and other military aircraft. 

2. A better understanding of the conditions that would create hypoxia-like symptoms at 
altitudes not normally associated with hypoxia, along with an evaluation of the guidance 
associated with the breathing air standards and the human response to operating in the 
F-22's extraordinary flight envelope with less than 90% supplied oxygen. 

3. Review the policies, processes, and procedural changes that occurred during the F-22's 
development and fielding, and evaluate the implications with respect to design 
limitations, risk analysis, program execution, and acquisition workforce. 

This report provides the results of that Study. 

Background 

Most modern day aircraft use an On-Board Oxygen Generation System (OBOGS) to 
provide breathing air to the crew. Beginning in the 1980s, these systems began to be chosen 
over liquid oxygen (LOX) systems due to reduced logistics footprint and reduced servicing 
requirements. These systems make use of the principal of Pressure Swing Adsorption, where 
cylinders of synthetic zeolite are able to concentrate the oxygen (O2) output by eliminating 
nitrogen from the breathing gas when the cylinder is pressurized and venting the nitrogen 
overboard when the pressure is vented. Depending on the temperature, pressure, and cycle time, 
these concentrators are able to produce O2 concentrations of 93-94%. 

The AOG Study Panel assessed the entire force of fighter aircraft of the USAF and US 
Navy. With the exception of the F-15C (which continues to use a LOX system) all of the other 
aircraft use some form of on-board oxygen generation provided by one of two corporations that 
dominate this market. A review of safety incident data showed that the F-22 aircraft was the 



v 



only aircraft with an abnormally high rate of hypoxia-like incidents whose cause could not be 
determined. All aircraft experienced low rates of incidents caused by a hardware failure, a hose 
obstruction, or mask failures; however, the F-22 was the only mission design series with a high 
rate of unknown cause incidents. 

While the pilots involved in these incidents reported a wide range of symptoms, they 
generally qualified as hypoxia-like. At the direction of the Air Combat Command (ACC) 
Commander, a Class E Safety Investigation Board (SIB) was formed to accomplish a fleet-wide 
assessment of oxygen generating systems and associated life support systems. This board 
thoroughly investigated each of the F-22 incidents of unknown cause and was unable to find a 
common root cause. 

An F-22 was lost on a night mission in Alaska in November of 2010, and the cause was 
unknown when this Study was initiated. As of May 201 1 the cause was still not identified, and 
in that month several hypoxia-like incidents at Elmendorf Air Force Base (AFB) led to the 
grounding of the F-22 aircraft fleet. Note: Eventual recovery of the aircraft data recorder 
showed the oxygen delivery system was not the cause of the aircraft loss, removing it as a 
primary case study for this inquiry. 

With this background, this AOG Quicklook Study was initiated in June 201 1. The SAB 
was tasked with also working with SIB members, the F-22 System Program Office (SPO), and 
ACC to identify necessary steps to return the F-22 to unrestricted operations. The 
"Return-To-Fly" section of this report defines those steps. 

Assessments 

The AOG Study Panel came to the view that the hypoxia-like incidents were being 
caused by the F-22 life support system either (1) delivering a lower amount of oxygen to the 
pilot than necessary to support normal performance, or (2) the system was producing or failing to 
filter toxic compounds in the breathing air. In the case of either hypothesis, the result would be 
hypoxia-like symptoms that could threaten safety of flight. 

In evaluating the system against the two hypotheses, the Panel assessed the technical 
performance of the F-22 life support system, the human effectiveness considerations of the 
system, and also the policies, processes, and procedures used to develop and acquire the system. 

The technical assessment of the F-22 life support system identified the following system 
design. The system is pressurized by bleed air from the ninth stage of the compressor. This air 
is then conditioned to the right temperature, humidity, and pressure by a series of heat 
exchangers that use either air or polyalphaolefm (PAO) as the thermal transport medium. The air 
is assumed to be "breathable" when it leaves the compressor and when it enters the OBOGS 
cylinders. There are no filters for potential contaminants, other than 0.6 micron filters on the 
entry and exit of the OBOGS unit, which are designed to filter particles from the breathing air. 
The output is then routed to the Breathing Regulator Anti-G (BRAG) valve and on to the pilot's 
mask. In the F-22, the pilot always breathes under a small positive pressure. A separate valve 
connects the emergency oxygen system (EOS) on the ejection seat to the pilot's mask. 

The system is unique in that, unlike all other OBOGS-equipped aircraft, a back-up 
oxygen system or plenum is not available to provide breathing continuity in the event of an 
OBOGS shutdown. In this situation, the pilot must manually activate the EOS, descend to an 



vi 



altitude where oxygen is not required, and land as soon as possible. The EOS activation handle 
was found to be difficult to locate and rapidly activate. If the pilot fails to act appropriately, loss 
of consciousness could result, likely leading to loss of the aircraft as the F-22 aircraft does not 
have an automatic ground collision avoidance system (AGCAS). Additionally, the system 
provides delayed warning to the pilot of a failure to deliver the right partial pressure of O2 and 
there is no indication of the pilot's oxygenation level. The system was fielded with no recurring 
maintenance or inspection requirements. It is a Fly-to- Warn/Fail system with servicing driven 
by a warning light or a pilot writing a maintenance discrepancy. (Note: The aircraft will also 
generate maintenance Fault Reporting Codes when the OBOGS malfunctions. These are 
recorded on the Data Transfer Cartridge that is downloaded after each flight.) 

The Study Panel benefitted from the availability of an F-22 aircraft at the Air Force 
Flight Test Center that had been specially instrumented to assess the performance of the entire 
system providing breathing air to the pilot. This aircraft flew operational profiles to duplicate 
those of incident aircraft in the field. Additionally, components of incident aircraft were 
removed and flown on the test aircraft. Data from these sorties are shown in this report (see 
Appendix C). As this Study was ending, two incident aircraft from the field were brought to 
Edwards AFB and also instrumented. 

During ground and flight tests, contaminants were found at levels well below those 
thought to be harmful. These contaminants contained elements of the ambient air, jet fuel, and 
PAO. As noted earlier, there was no contaminant filter in the breathing path. Tests have shown 
that the OBOGS itself can filter some elements and concentrate others, as it does with oxygen. 

The assessment of the environmental control system (ECS) and life support system 
development programs indicated a major shortfall in the modeling and simulation of the system 
to determine performance under degraded conditions or in the presence of contaminants in the 
breathing gas. This assessment also identified major shortfalls in the application of Human 
System Integration (HSI) principles, availability of appropriate breathing standards, and a 
comprehensive understanding of the aviation physiology implications of sustained operations at 
high altitude without a full pressure suit. 

The F-22 was developed during a period of major changes in the Air Force acquisition 
process. The majority of the Department of Defense military specifications and standards were 
rescinded and the acquisition workforce was reduced in favor of increased industry 
responsibility. A refined program management structure delegated many decisions to Integrated 
Product Teams (IPTs) for non safety-critical functions. These changes left major uncertainties as 
to what was an "inherently governmental responsibility." Additionally, the program underwent 
several major restructures driven by cost and funding constraints, to include major reductions in 
the size of the F-22 program office. 

These assessments led the Study Panel to make the following Findings and 
Recommendations to both mitigate identified risks in allowing the F-22 to return to flight and to 
provide the data necessary to identify the root cause(s) of these hypoxia-like incidents. 



vii 



Findings 

1. The F-22 OBOGS, Back-up Oxygen System (BOS), and EOS were not classified as 
"Safety Critical Items." 

• The Life Support System IPT eliminated the BOS to save weight. 

• The ECS IPT designed an Air Cycle Machine bypass to provide bleed air to the 
OBOGS in the event of an ECS shutdown. 

• The Emergency Oxygen System was deemed to be an adequate Backup Oxygen 
System. 

• The ECS IPT decided to forgo the Air Cycle Machine bypass. 

• With an ECS shutdown, the pilot's flow of breathing air is cut-off thus requiring the 
pilot to activate the Emergency Oxygen System to restore the flow of breathable air. 

• Interrelated and interdependent decisions were made without adequate cross-IPT 
coordination. 

2. Over the past 20 years, the capabilities and expertise of the USAF to perform the critical 
function of Human Systems Integration have become insufficient, leading to: 

• The atrophy of policies/standards and research and development expertise with 
respect to the integrity of the life support system, altitude physiology, and aviation 
occupational health and safety. 

• Inadequate research, knowledge, and experience for the unique operating 
environment of the F-22, including routine operations above 50,000 feet. 

• Limited understanding of the aviation physiology implications of accepting a 
maximum 93-94% oxygen level instead of the 99+% previously required. 

• Specified multi-national air standards, but deleted the BOS and did not integrate an 
automated EOS activation system. 

• Diminution of Air Force Materiel Command (AFMC) and Air Force Research 
Laboratory (AFRL) core competencies due to de-emphasis and reduced workforce to 
near zero in some domains. 

3. Modeling, simulation, and integrated hardware-in-the-loop testing to support the 
development of the F-22 life support system and thermal management system were 
insufficient to provide an "end-to-end" assessment of the range of conditions likely to be 
experienced by the F-22. 

• Engine-to-mask modeling and simulation was non-existent. 

• Dynamic response testing across the full range of simulated environments was not 
performed. 

• Statistical analysis for analyzing and predicting system performance/risk was not 
accomplished. 



via 



• Performance of OBOGS when presented with the full range of contaminants in the 
ECS air was not evaluated. 

4. The F-22 life support system lacks an automatically-activated supply of breathable air. 

• ECS shutdowns are more frequent than expected and result in OBOGS shutdown and 
cessation of breathing air to the pilot. 

• The F-22 is the only OBOGS-equipped aircraft without either a BOS or a plenum. 

• The "OBOGS Fail" light on the integrated caution, advisory, and warning system 
(ICAWS) has a 12-second delay for low oxygen, providing inadequate warning. 

• When coupled with a rapid depressurization at the F-22's operational altitudes, the 
'Time of Useful Consciousness" can be extremely limited. 

• The EOS can be difficult to activate, provides inadequate feedback when successfully 
activated, and has limited oxygen duration. 

5. Contaminants identified in the ongoing Molecular Characterization effort have been 
consistently measured in the breathing air, but at levels far below those known to cause 
health risks or impaired performance. 

• Contaminants that are constituents of ambient air, Petroleum, Oils and Lubricants, 
and polyalphaolefm are found throughout the life support system in ground and flight 
tests. 

• OBOGS was designed to be presented with breathable air and not to serve as a filter. 

• OBOGS can filter some contaminants and there is evidence it may concentrate others. 

6. The OBOGS was developed as a "fly-to- warn/fail" system with no requirement for initial 
or periodic end-to-end certification of the breathing air, or periodic maintenance and 
inspection of key components. 

• Engine bleed air certified "breathable" during system development. 

• OBOGS units are certified at the factory. 

• No integrated system certification. 

• No recurring Built-in Test, inspections, or servicing. 

7. Given the F-22's unique operational envelope, there is insufficient feedback to the pilot 
about the partial pressure of oxygen (PPO2) in the breathing air. 

• Single oxygen sensor well upstream of the mask. 

• 12-second delay in activating the ICAWS when low PPO2 is detected. 

• Inadequate indication of EOS activation when selected. 

• No indication of pilot oxygen saturation throughout the F-22 flight envelope. 



ix 



8. The F-22 has no mechanism for preventing the loss of the aircraft should a pilot become 
temporarily impaired due to hypoxia-like symptoms or other incapacitating events. 

• Disorientation, task saturation, and/or partial impairment from hypoxia could result in 
loss of the aircraft and possibly the pilot. 

9. The F-22 case study illustrates the importance of identifying, developing, and 
maintaining critical institutional core competencies. 

• Over the last two decades, the Air Force substantially diminished its application of 
systems engineering and reduced its acquisition core competencies (e.g., systems 
engineering, HSI, aviation physiology, cost estimation, contracting, and program and 
configuration management) to comply with directed reductions in the acquisition 
work force. 

• By 2009, the Air Force had recognized this challenge and developed a comprehensive 
Acquisition Improvement Plan (AIP) and an HSI plan. 

• Although the AIP has been implemented, the HSI plan is early in its implementation. 

• A clear definition of "inherent government roles and responsibilities" is not apparent. 

Recommendations 

1. Develop and install an automatic Backup Oxygen Supply in the F-22 life support system. 
[Office of Primary Responsibility (OPR): ACC] [Office of Collateral Responsibility 
(OCR): Air Force Life Cycle Management Center (AFLCMC)] 

• Consider a 100% oxygen BOS capability unless hazardous levels of contaminants in 
OBOGS product air can be ruled out. 

2. Re-energize the emphasis on Human Systems Integration throughout a weapon system's 
lifecycle, with much greater emphasis during Pre-Milestone A and during Engineering 
and Manufacturing Development phases. [OPR: AFMC, Assistant Secretary of the Air 
Force (Acquisition) ( SAF/AQ)] 

• Identify and reestablish the appropriate core competencies. [OPR: SAF/AQ] [OCR: 
AFMC, Air Force Surgeon General (AF/SG)] 

• Develop the capability to research manned high altitude flight environments and 
equipment, develop appropriate standards, oversee contractor development, and 
independently certify critical, safety-of-flight elements. [OPR: AFRL, AFLCMC] 

3. Establish a trained medical team with standardized response protocols to assist safety 
investigators in determining root cause(s) for all unexplained hypoxia-like incidents. 
[OPR: AFLCMC, AF/SG] [OCR: AFRL] 

4. Develop and implement a comprehensive Aviation Breathing Air Standard to be used in 
developing, certifying, fielding, and maintaining all aircraft oxygen breathing systems. 
[OPR: SAF/AQ] [OCR: AFMC, AFRL, AFLCMC] 



x 



5. Create and validate a modeling and simulation capability to provide end-to-end 
assessments of life support and thermal management systems. [OPR: AFMC] 

• The initial application should be the F-22 followed by the F-35. 

6. Improve the ease of activating the EOS and provide positive indication to the pilot of 
successful activation. [OPR: ACC] [OCR: F-22 SPO] 

7. Complete the Molecular Characterization to determine contaminants of concern. [OPR: 
AFRL, ACC, F-22 SPO] 

• Where appropriate, alternative materials should be considered to replace potential 
sources of hazardous contaminants. [OPR: Deputy Chief of Staff for Logistics, 
Installations, and Mission Support (AF/A4/7), AF Petroleum Agency] 

• Develop and install appropriate sensor and filter/catalyst protection. 

8. Develop and implement appropriate inspection and maintenance criteria for the OBOGS 
and life support system to ensure breathing air standards are maintained. [OPR: ACC] 
[OCR: F-22 SPO] 

9. Add a sensor to the life support system, post-BRAG (Breathing Regulator Anti-G), which 
senses and records oxygen pressure and provides an effective warning to the pilot. [OPR: 
ACC] [OCR: F-22 SPO] 

10. Integrate pilot oxygen saturation status into a tiered warning capability with consideration 
for automatic Backup Oxygen System activation. [OPR: ACC] [OCR: AFMC] 

11. Develop and install an AGCAS in the F-22. [OPR: ACC] [OCR: F-22 SPO] 

12. Clearly define the "inherent governmental roles and responsibilities" related to USAF 
acquisition processes and identify the core competencies necessary to execute those 
responsibilities. [OPR: SAF/AQ, Assistant Secretary of the Air Force (Financial 
Management and Comptroller) (SAF/FM), Assistant Secretary of the Air Force 
(Installations, Environment, and Logistics) (SAF/IE), AF/A4/7] 

13. Create a medical registry of F-22 personnel who are exposed to cabin air or OBOGS 
product gas, and also initiate epidemiological and clinical studies that investigate the 
clinical features and risk factors of common respiratory complaints associated with the 
F-22. [OPR:AF/SG] 

14. Establish a quarterly follow-up to ensure SAB recommendations are implemented in a 
timely fashion or to respond to any event of significance. Note: The SAB is available for 
continued support if desired. [OPR: Headquarters, USAF] 



xi 



Return-to-Fly 



Near-Term: 

• Implement improved access to, and ease of activation of, the EOS. 

• Implement an independent post-BRAG O2 sensor providing indication, warning, and 
recording capability. 

• Field helmet-mounted pulse oximeter. 

• F-22 Life Support Systems Task Force should consider installing carbon monoxide and 
carbon dioxide detectors in the F-22 cockpits. 

• F-22 Life Support Systems Task Force should consider using a vacuum canister during 
maintenance engine runs and assess the contents should there be an incident. 

• Leverage the National Aeronautics and Space Administration, or similar independent 
capabilities, to develop and implement the appropriate post-incident protocols with 
greater emphasis on forensic analysis of the entire life support and cabin pressurization 
systems. 

• Analyze data gathered to determine effectiveness of the C2A1 filter for safety and data 
collection. 

• F-22 Life Support Systems Task Force and 711 Human Performance Wing identify the 
need for contaminant mitigation measures for both OBOGS and cockpit breathing air. 

Long-Term: 

• Install an automatically-activated Backup Oxygen System. 

• Determine, through further data analysis, the need for aircraft mounted measurement and 
mitigation of contaminants in the breathing air. 

• Develop and install an AGCAS for the F-22. 

Summary 

The Air Force Scientific Advisory Board and the F-22 Life Support Systems Task Force 
have not yet determined the root cause(s) of the incidents, but have identified and mitigated a 
number of risks. While the data evaluated by this team identified minor system anomalies and a 
lack of robustness in the F-22 life support system's configuration, system performance exceeded 
pilot physiological needs. 

Contaminants identified were at levels far below those known to be harmful to humans. 
The measures taken to protect the crews and gathering of appropriate data are providing 
substantive and valuable information and have narrowed the possibilities while maintaining 
combat capability. Continuing an aggressive approach with all F-22 ECS/OBOGS anomalies 
will be critical in resolving the unexplained physiological events. Implementing the Findings 
and Recommendations, along with the considerations presented in the Transition Operations 
section, should provide the F-22 with a significantly improved margin of safety and operational 
effectiveness. 



xii 



Table of Contents 



Foreword iii 

Executive Summary v 

Table of Contents xiii 

Table of Figures xv 

Table of Tables xvii 

Section 1 : Introduction 1 

Section 2: Assessments 11 

Engineering 13 

Human Effectiveness 27 

Policies, Plans, and Procedures 35 

Section 3: Return to Fly 43 

Section 4: Findings 47 

Section 5: Recommendations 57 

Section 6: Transition Operations 67 

Section 7: Summary 71 

Appendix A: United States Air Force and Navy Aircraft Oxygen Generation (AOG) 

Systems 73 

Appendix B: Molecular Characterization 87 

Appendix C: F-22 Combined Test Force Aircraft Instrumentation and 

Test Activities 107 

Appendix D: Human Systems Integration and the F-22's Environmental Control 

System (ECS) and Life Support System (LSS) 115 

Appendix E: Effect of Funding and Personnel Reductions: Human Performance 

Competencies 121 

Appendix F: F-22 Program Schedule 135 

Appendix G: Policies, Plans, and Procedures: Interviewees 137 

Appendix H: Study Hypotheses and Questions Examined 141 

Appendix I: Terms of Reference 153 

Appendix J: Study Members 155 

Appendix K: Study Meetings and Briefings 157 

xiii 



Appendix L: Glossary 159 

Appendix M: Acronyms and Abbreviations 185 

Appendix N: Bibliography 197 

Appendix O: Initial Distribution 233 



xiv 



Table of Figures 



Figure A-l F-15A-D Legacy Liquid Oxygen (LOX) Converter 73 

Figure A-2 USAF Hypoxia Rates for Selected Aircraft 74 

Figure A-3 F-15E Molecular Sieve Oxygen Generation System 75 

Figure A-4 F-16 Block 50 OBOGS 76 

Figure A-5 F-18 Oxygen Concentrator System 77 

Figure A-6 AV-8B Oxygen Concentrator 78 

Figure A-7 T-6A Texan II Oxygen Concentrator 79 

Figure A-8 B-1B Lancer Molecular Sieve Oxygen Generation System 80 

Figure A-9 B-2A Spirit Oxygen Generation and Distribution System 81 

Figure A- 10 V-22 Osprey Oxygen/Nitrogen Generation System 82 

Figure A-l 1 F-35 On-Board Oxygen Generating System 83 

Figure C-l Aircraft Instrumentation Diagram 108 

Figure C-2 Pilot-Mounted Instrumentation 110 

Figure E-l Losses of Military Officer, Enlisted, and Civilian Personnel Authorizations 

During the Period from September 1996 to September 2000 128 

Figure F-l F-22 Raptor Program Schedule Showing Acquisition Milestones 
and Phases, Major Program Events, and Aircraft Lot Deliveries 
from Fiscal Year (FY) 1986-2013 135 



xv 



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xvi 



Table of Tables 



Table A- 1 Comparison of Various OBOGS in US AF and USN Aircraft 85 

Table B- 1 Hazard Quotients and Hazard Index for Chemicals Measured 

at OBOGS Inlet 94 

Table B-2 Hazard Quotients and Hazard Index for Chemicals Measured 

at OBOGS Outlet 96 

Table C-l Aircraft Instrumentation Added for Investigation 108 

Table C-2 Human Instrumentation 109 

Table C-3 F-22 OBOGS Phase II Flight Test Profile A 110 

Table C-4 F-22 OBOGS Phase II Flight Test Profile E 112 

Table C-5 F-22 OBOGS Phase II Flight Test Profile G 112 

Table C-6 Aircraft Configurations and Flight Profiles 113 

Table C-7 Ground and Flight Test Dates 114 

Table E- 1 US AF Science and Technology Budgets for Fiscal 

Years (FY) 1999-2003 126 

Table G-l Scientific Advisory Board Aircraft Oxygen Generation 

Study Panel Interviewees 139 



xvii 



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XVIII 



Section 1 : Introduction 



Air Force Scientific Advisory Board 

Integrity - Service - Excellence 

Aircraft Oxygen Generation 
Quicklook Study 



Gen Gregory S. Martin, USAF (Ret), Chair 
Lt Gen George K. Muellner, USAF (Ret), Vice Chair 

January 24, 2012 




The United States Air Force (USAF) Scientific Advisory Board (SAB) was asked to 
conduct a Quicklook Study on "Aircraft Oxygen Generation" (AOG). Over the last twenty-five 
years, aircraft oxygen support systems for the crew have migrated from dilution systems using 
ground-serviced liquid oxygen to on-board oxygen generation systems (OBOGS) using 
molecular sieve oxygen concentrators. These systems significantly reduce the logistics footprint 
and require limited servicing between missions. 

Over the 2008-2011 period, there were a number of hypoxia- like incidents of unknown 
cause in the F-22 aircraft that may be related to the OBOGS or its installation. Therefore, the 
Secretary of the Air Force requested this Study of system safety issues involving OBOGS on the 
F-22, and the oxygen generation systems on other aircraft, to ensure that the appropriate steps are 
being taken to enhance flight safety of these aircraft. The Study formally began in June 2011 
and was completed at the end of January 2012. Interim status reports were provided to the 
Secretary of the Air Force and the Air Force Chief of Staff on July 1, 201 1; to the Chief of Staff 
on September 2, 201 1; and to the Secretary and the Chief of Staff on September 12, 201 1. The 
final briefing was presented to the entire SAB on January 11, 2012 and was approved. A final 
briefing was provided to the Secretary and Chief of Staff on January 24, 2012. The final outbrief 
slides from the Study, with text annotations and supporting appendices, are provided. 



1 



The recommendations made are based on findings reached from information discussed 
and reviewed in the explanatory briefing slides included in this report, and information resources 
listed in the corresponding appendices. 



2 



Outline 




■ Introduction 




■ Assessments 




■ Engineering 




■ Human Effectiveness 




■ Policies, Processes & Procedures 




■ Return to Fly 




■ Findings 




■ Recommendations 




■ Transition Operations 




■ Summary 







The USAF SAB was asked to put together a Study Panel to assist the Air Force in 
determining the root cause, or causes, of a number of unexplained hypoxia-like incidents in the 
F-22 fleet since 2008. 

The conduct of this AOG Study has differed from most SAB studies, in that the Study 
Panel dealt with an ongoing operational challenge that is still accumulating data with regard to 
the F-22's life support system. 

Further, as will be discussed, the Air Combat Command (ACC) established a Class E 
Safety Investigation Board (SIB) in January of 201 1 to initiate a complete review of the F-22 life 
support system and the growing number of hypoxia-like incidents that started in 2008. After five 
months of focused investigation, the Safety Investigation Board President recommended the 
Secretary of the Air Force initiate a Broad Area Review of the F-22 life support system, which 
resulted in the SAB Quicklook Study on Aircraft Oxygen Generation. 

This report will provide the background for the Study and then assessments of the key 
issues from an Engineering, Human Effectiveness, and Policy, Processes and Procedures 
perspective. These assessments provide the foundation for the Study's Findings and 
Recommendations, and also for the actions that led to returning the F-22 to normal operations. 



3 



Aircraft Oxygen Generation 
Study: Charter 

■ Continue the evaluation of the F-22 2 system to include developing means to gather 
dynamic in-flight information to identify the root cause of reported hypoxia incidents 

■ Review and validate all associated aircrew flight equipment affiliated with OBOGS- 
equipped aircraft 

■ Evaluate further investigation into contaminants that potentially impact OBOGS 
operation and follow-on performance effects on aircrew 

■ Priority given to F-22 aircraft but expanding the scope to include the F-16, A-10, 
F-15E, B-1, B-2, CV-22, T-6, F-35, F-18 and other aircraft 

■ Examine those incidents that are occurring in flight regimes which are normally 
considered unlikely for a hypoxic event (e.g., 8000' cabin attitude pressures) 

■ Revalidate and make recommendations to clarify guidance for Air Standards with 
specific guidance on effect of systems designed to minimum acceptable standards 

■ Direct and evaluate, if able, human response to high altitude, rapid cabin altitude 
changes and rapid decompression with less than 90% supplied 2 

■ Review and validate the implementation of performance based contract acquisition 
programs and risk analysis protocols 

■ Evaluate OBOGS, and life support systems in general, to determine commonalities 
and acquisition philosophy across MDS and ID design limitations or key assumptions 




This Study was initiated because the Air Force had been unable to determine the cause of 
a number of sporadic hypoxia-like incidents that were reported by F-22 pilots over the past 
several years. 

As a result of the normal Air Force safety investigation procedures used for each 
hypoxia-like incident that occurred from 2008 until the present, as well as the extensive efforts of 
the Class E SIB initiated in January 2011, the SAB AOG Study Charter was quite specific and 
detailed about the Study Panel's task. Of note was the need to conduct in-flight tests and other 
data gathering to determine root cause, or root causes. The Charter guided the AOG Study Panel 
to cover three areas: 

1. Continue the ongoing efforts to determine root cause(s), to include: Gathering data 
during dynamic, in-flight testing; full reviews of both the life support equipment and 
the aircraft's potential for passing contaminants into the cockpit and/or breathing air; 
and finally, to better understand the similarities and differences between the F-22 
oxygen generating system and other military aircraft. 

2. A better understanding of the conditions that would create hypoxia-like symptoms at 
altitudes not normally associated with hypoxia, along with an evaluation of the 
guidance associated with the breathing air standards and the human response to 
operating in the F-22's extraordinary flight envelope, with less than 99% supplied 
oxygen. 



4 



3. Review the policies, processes, and procedural changes that occurred during the 
F-22's development and fielding, and evaluate the implications with respect to design 
limitations and risk analysis. 

The Terms of Reference for this Study are summarized above. The full AOG Study 
Terms of Reference are provided in Appendix I of this report. 



5 



AOG Study Team 




Study Leadership 

Gen Gregory Martin, USAF (Ret) 
Lt Gen George Muellner, USAF (Ret) 

SAB Members 

Dr David Moore 

SAB Consultants 

Gen Thomas Moorman, USAF (Ret) 
Honorable Dr Lawrence Delaney 
Maj Gen Joseph Anderson, USMC (Ret) 
Mr James Brinkley, SES (Ret) 
Peter Demitry, MD, MPH 



General Officer Advisors 

Maj Gen Noel Jones, USAF 
Maj Gen Robin Rand, USAF 

AF Participants 

Dr Thomas Ehrhard, SES, CC-SA 
Col Eric Kivi, USAF, AFSC 

AFSAB Secretariat 

Lt Col Edward J. Ryan, USAFR 
Lt Col Norman Shelton, USAF 
Lt Col Matthew Zuber, USAF 
Maj Christopher Forrest, USAF 
Maj Brian Stahl, USAF 
Maj Ryan Maresh, USAF 
Capt Andrew Anderson, USAF 
Mr William Quinn 



The membership of the USAF SAB AOG Quicklook Study is listed above. In addition to 
the AF SAB Study Panel members and consultants, there was General Officer, Air Force Air 
Staff, and Air Force Safety Center representation. Additional information on Study Panel 
members is presented in Appendix J. 

The Study Panel was ably assisted by SAB Secretariat support staff and volunteer 
executive officers from Office of the Assistant Secretary (Acquisition), the Air Force Flight Test 
Center, and the USAF Academy. The Study Panel is indebted to these individuals for their 
dedication and hard work in support of the AOG Study. 



6 




Air Force 

AF/A3/5/A4/A9/JA/SG/ST 

SAF/AQR/AQX 

AF Safety Center 

AFHSIO 

AFMC/SG/SE 

AFFTC/412 TW/F-22 CTF/95 AMDS 

46 TW 

ASC/F-22 SPO/EN/WI/WW/WN 
AFRL/711 HPW/RH/USAFSAM 
ACC/A3/A4/SG 
9AF/SE 

1 FW/1MXG/AFETS 
AETC/A3/SG 

59 MDTS 

43 FS 
AFIT 

3 FW/3AOG/3AMXS 
302 FS (AFRes) 

Previous F-22 Program Managers & 
Chief Engineers 



Other DoD 
F-35 JPO 
OUSD(ATL)/JSF 
NAVAIR 
NAWC 

Contractors 
Boeing 

Cobham Mission Systems 

Honeywell 

Lockheed Martin 

Mayo Clinic 

Pratt & Whitney 

Wyle 

Columbia Labs 

Other Govt / FFRDCs/Universities 
NASA Dryden Flight Research Center 
NASA Houston Johnson Space Center 
University of Colorado (Kosnett) 
University of Tennessee (Parke) 
Sandia National Laboratories (Nenoff) 
Lawrence Livermore National Laboratories 
Edgewood Chemical Biological Center 



The AOG Study Panel received a large number of briefings and perspectives on various 
aircraft OBOGS standards and designs in general; the F-22 and F-22 OBOGS in particular, pilot 
physiological performance under various conditions, and many other related issues in the course 
of the Study, from within and outside of the United States Government. The Study members 
visited several Air Force bases and facilities, including the AF Flight Test Center at Edwards Air 
Force Base (AFB), California, the 1 st Fighter Wing at Langley AFB, Virginia, and the 
Aeronautical Systems Center at Wright-Patterson AFB, Ohio. 

The Panel received briefings from the Air Force Safety Center, the F-22 Combined Test 
Force, the F-22 System Program Office (SPO), the F-35 Joint Program Office, and the USAF 
School of Aerospace Medicine. In addition, inputs were sought from current and past F-22 
System Program Directors and F-22 Program Chief Engineers. 

The Study Panel members benefitted from hearing from the contractors that are 
responsible for the F-22 and its systems, or who had other useful information to offer including 
Lockheed Martin, Boeing, Pratt and Whitney, Cobham Mission Systems, and Honeywell. The 
Panel members also benefitted from hearing from representatives from the Naval Air Warfare 
Center and the Naval Air Systems Command, as well as the National Aeronautics and Space 
Administration's (NASA) Dryden Flight Research Center and Johnson Space Center. 

A more detailed listing of the contributing organizations and experts is included in 
Appendix K. 



7 



Motivation for SAB Study 




USAF Hypoxia Incident Rate 
per 100,000 Flight Hrs 




• Significant increase in 
F-22 hypoxia incidents 

• Cause for most was 
unknown 

• F-22 Class A Mishap 
(Nov 10) with an 
unknown cause (at 
that time) 

• ACC convenes Class E 
SIB, January 2011 

• F-22 aircraft grounded, 
May 2011 



The Secretary of the Air Force's reason for requesting the SAB Study is reflected in this slide. 
As the slide reflects, the F-22 had a higher hypoxia incident rate than other fighter aircraft. Of 
more concern was the fact that the majority of the F-22 incidents could not be traced to a known 
cause or system failure. 

An F-22 was lost on a night mission in Alaska in November of 2010, and the cause was 
unknown when this AOG Study was initiated. As of May 2011, the cause was still not 
identified, and in that month several hypoxia- like incidents at Elmendorf AFB, Alaska led to the 
grounding of the F-22 aircraft fleet. Eventual recovery of the mishap aircraft's data recorder 
showed the oxygen delivery system was not the cause of the aircraft loss, removing it as a 
primary case study for this inquiry. 

Following the mishaps in Alaska, ACC convened a Class E SIB focused on a fleet-wide 
assessment of oxygen generating systems and associated life support systems with emphasis on 
the F-22. A Broad Area Review was considered following the SIB; however a decision was 
made to engage in this SAB Study. 



8 



Hypotheses 



1. The F-22 oxygen delivery system is failing to deliver 
adequate 2 to the pilot, resulting in hypoxia 
symptoms that threaten safety of flight 




2. The F-22 oxygen delivery system is either producing 
or failing to filter a toxic compound(s) in the 2 to the 
pilot resulting in hypoxia-like symptoms that threaten 
safety of flight 



The AOG Study Panel came to view that the hypoxia-like incidents were being caused by 
the life support system either (1) delivering a lower amount of oxygen to the pilot than necessary 
to support normal performance, or (2) the system was producing or failing to filter toxic 
compounds in the breathing air. In either case, the result would be hypoxia-like symptoms that 
could threaten safety of flight. 

Each of these two main hypotheses had six sub-hypotheses, along with a series of 
questions that guided the Study effort. Later in this report a slide presents the essence of the 
sub-hypotheses and what has been learned, thus far, with regard to proving or disproving them, 
and what actions are being taken to mitigate the risks. 

A large number of hypotheses and sub-hypotheses were developed by the AOG Panel in 
the course of its inquiry. As they were developed and refined each was analyzed and responses 
provided by a technical team led by the F-22 SPO. The hypotheses and the detailed 
discussion/response for each, as prepared and presented by the technical team led by the F-22 
SPO, are contained in Appendix H of this report. 



9 



(This Page Intentionally Left Blank) 



10 



Section 2: Assessments 



uutiine 


fJ>ABl 


■ Introduction 




mm nOOvOwl 1 1 vl 1 Iw 




■ Engineering 




■ Human Effectiveness 




■ Policies, Processes & Procedures 




■ Return to Fly 




■ Findings 




■ Recommendations 




■ Transition Operations 




■ Summary 







As the AOG Study Panel formed up, it was organized to approach the Terms of Reference along 
an assessment methodology that considered (1) engineering and technical aspects of the F-22 
OBOGS, as well as comparisons with other Department of Defense (DoD) aircraft equipped with 
an OBOGS; (2) the set-up of the system with regards to how well it contributed to the human 
effectiveness of the crews operating the F-22 (including human systems integration, toxicology, 
and modeling and simulation; and (3) the implications of the policies, processes and procedures 
used to develop, field and sustain the F-22 and its life support system. 

As a result of the initial assessments of a fatal F-22 mishap in Alaska in November 2010, 
and two incidents that occurred at Elmendorf AFB in early May 2011, the F-22 was grounded 
and great attention was focused on testing many of the components contributing to the F-22's life 
support systems. Once the SIB had determined that they understood the components' 
performance characteristics, a specific protocol was established for conducting a series of 
dynamic, in-flight tests to ensure the accurate data collection from a system performing in an 
end-to-end fashion. Until that point, the Air Force had not tested and measured the F-22 life 
support system end-to-end — either in a comprehensive modeling and simulation environment or 
in the air with a specifically instrumented aircraft. 



11 



Building on the lessons of the SIB and the data gathered during the dynamic in-flight 
testing conducted on a specially-instrumented test aircraft at Edwards AFB, the Study Panel 
developed a comprehensive "Return-to-Fly" program that will be detailed further in a few 
subsequent slides. This program was designed after a statistical assessment indicated that as the 
test sorties were being flown, it was quite unlikely that another hypoxia-like event might occur, 
and therefore, determining the root cause(s) could be highly problematic until many more sorties 
were flown. With that in mind, the Study Panel determined that a carefully planned "Return to 
Fly" program could be developed that would "Protect the Crews" and "Continue to Collect" 
data, and suggested the Air Force form a "Task Force" team to ensure a standard approach in 
gathering and analyzing the data for each incident that might occur during this phase. 

Since initiation of the Return to Fly program in mid-September 201 1, the Air Force flew 
about 7,000 sorties as of the date of this report. A discussion of what Breathing Air Anomalies 
have occurred follows. 

From the data gathered to date, the Study Panel believes it has been able to properly 
narrow the field of potential causes for the hypoxia-like incidents, such that the Task Force and 
continuation of the SIB efforts will be able to eventually determine the root causes by reviewing 
the Study Panel's Findings and implementing its Recommendations. But in addition to dealing 
with the Findings and preparing to implement the Recommendations, the Study Panel has made a 
series of suggestions to the Task Force regarding the transition from the "Return to Fly Phase" to 
the "Normal Operations" phase for F-22 operations. 



12 



Outline 




■ Introduction 




■ Assessments 




■ Engineering 




■ Human Effectiveness 




■ Policies, Processes & Procedures 




■ Return to Fly 




■ Findings 




■ Recommendations 




■ Transition Operations 




■ Summary 







The AOG Study Panel looked at several engineering/technical areas in the course of the 
Study. The following slides present the main technical areas reviewed and the Panel's 
observations regarding the F-22 Environmental Control System (ECS) / Life Support System 
(LSS) and the initial safety / design approaches that were employed during system development, 
use of modeling and simulation, and the scheduling of the F-22 OBOGS product. 



13 




This slide shows the schematic for the F-22 ECS/LSS. The LSS is powered by bleed air 
from the ninth-stage of the Fl 19 engine's compressor, or from the auxiliary power unit (APU) on 
the ground. The air is then conditioned to the proper pressure (35 pounds per square inch (psi)), 
temperature, and humidity by heat exchangers that have polyalphaolefm, a synthetic lubricant 
used as a coolant, or air as a thermal transport medium. The Air Cycle Machine (ACM) 
prioritizes the bleed air flow to Life Support and Avionics cooling. 

The bleed air entering the OBOGS unit is assumed to be breathable (i.e., free of harmful 
contaminants) as the air handling and coolant systems are each self-contained systems, with the 
contents of each never coming in direct contact with the other. The quality of the breathing air 
was tested and certified at the ninth-stage bleed port on engine qualification during the F-22 
Engineering and Manufacturing Development (EMD) phase. Individual engine bleed air is not 
tested on engine delivery or in recurring maintenance. The system contains no filter designed to 
remove potential contaminants in the breathing air. Initially, the system was designed with a 
chemical-biological filter, but it was removed during EMD. The OBOGS unit has an inlet filter 
(0.6 micron) that is designed to filter particles. In testing, the OBOGS unit demonstrated the 
ability to filter some contaminants while concentrating others. 

A single sensor schedules the OBOGS cycles to respond to inputs from the cabin altitude 
sensor and provides system warning to the F-22's Integrated Caution, Advisory, and Warning 
System (ICAWS) when the oxygen production is below a software-defined warning band for 12 
seconds. A complete analysis of the entire system is limited by the inability to model the flow 
process from the engine's Bleed Air Port to the pilot's mask. 



14 



Assessment - Engineering 
F-22 Life Support Diagram 





This slide diagrams the F-22 Life Support System starting with the conditioned air from 
the F-22 ECS. The system requires engine bleed air that is properly conditioned to the right 
pressure, temperature, and humidity. Unlike most other aircraft oxygen generation systems, the 
breathing air to the F-22 pilot is not diluted with cockpit air to obtain the appropriate oxygen 
partial pressure (PPO2) necessary to maintain physiological function at a particular altitude, but 
rather it is concentrated to the necessary PPO2 by controlling the cycling of the OBOGS. Also 
unlike other aircraft, the F-22 pilot is always breathing under a positive pressure (about 1 psi on 
the ground). 

Another difference between the F-22 and other existing systems is that the F-22 does not 
incorporate a Post-OBOGS Back-up Oxygen System (BOS), Standby Oxygen System, or a 
plenum (air reservoir) to provide breathing continuity while dealing with an OBOGS shutdown. 
With a shutdown of the F-22 OBOGS, the pilot must activate the F-22's Emergency Oxygen 
System (EOS), which provides a limited (5-20 minutes) supply of 100% oxygen to the pilot. 

The F-22 originally included a self-regenerating Standby Oxygen System, now called 
BOS, but it was removed as a weight-saving measure during development. The logic behind the 
decision was that the EOS provided adequate back-up in the event of an OBOGS shut-down. 
That decision saved approximately 15 pounds and was approved by the F-22 Life Support 
System Integrated Product Team (IPT) in 1992. This decision was made based on the 
availability of the EOS and the expectation that OBOGS shutdowns would be an unlikely 
occurrence. Additionally, the ECS IPT was designing a bypass of the ACM that would ensure 
the OBOGS received bleed air if ECS system failure occurred. This modification was not 
incorporated and ECS shutdowns have occurred more frequently than was anticipated. 



15 



Output from the OBOGS flows to the Breathing Regulator Anti-G (BRAG) valve where 
it is provided to the pilot's mask at the proper pressure. This valve also regulates flow to the 
anti-G vest. A separate isolation valve routes the emergency oxygen to the pilot's mask when 
the EOS is activated. When the EOS is consumed, the pilot will revert to OBOGS output if the 
system is functioning. 



16 



Assessment - Engineering 
OBOGS Schematic Diagram 




Air supply 



93-94% : 




(Maximum) supply 



■ Efficiency Factors: Temperature, Pressure, Affinity 

■ Internal Dilution Control 

■ Not Designed as a Filter 



This slide shows the schematic for the F-22's OBOGS. The F-22 OBOGS consists of 
three molecular sieve canisters that incorporate 13X zeolite, a synthetic zeolite that absorbs 
nitrogen from the bleed air, thereby producing oxygen-rich breathing gas. The OBOGS has a 0.6 
micron filter on the inlet and exit ports designed to filter particles; however, the system contains 
no filter designed to remove potential contaminants in the breathing air. Zeolite has been shown 
to filter some contaminants and concentrate other chemicals such as argon. Argon in this case is 
not a contaminant, but rather it is a normal constituent of air that is concentrated, like oxygen, 
when nitrogen is removed. 

The F-22 OBOGS does not always produce oxygen at its maximum rate, but rather 
concentrates oxygen from engine bleed air to obtain the appropriate PPO2 necessary to maintain 
physiological function at a particular altitude. OBOGS performs the concentrating function by 
controlling the length of the concentration cycle — a shorter charge cycle and a longer vent cycle 
produces a higher concentration of oxygen. The F-22 system modulates the cycling of the three 
zeolite canisters to produce a continual flow of breathing air at the proper PPO2, as determined 
by cabin altitude. System performance is dependent on pressure differentials across the zeolite 
bed, with the input pressure regulated to 35 psi and the outlet pressure to 30 psi. In the F-22, if 
the ECS shuts down the bleed air flow to the OBOGS, the pilot becomes starved of air, which 
requires activation of the EOS and curtailment of the mission. As noted previously, the F-22 
BOS was traded away as a weight-saving measure on the assumption that bleed air would always 
be available. All other OBOGS-equipped aircraft life support systems incorporate a BOS or 
plenum downstream of the OBOGS unit to provide breathing continuity in the event of an 
OBOGS shutdown for some period of time. The 1992 Trade Study determined that the EOS, 



17 



located on the ejection seat, was adequate as a back-up. This was highlighted on the previous 
slide. 



18 



Assessment - Engineering 
Emergency Oxygen System (EOS) 





Original F-22 EOS green 
ring installation 




Initial EOS green ring design 
had lap belt routing issues 



Final EOS green ring 
design with center 
bar-currently being 
installed in F-22 fleet 




Emergency Oxygen System 

The primary purpose of an emergency oxygen system is to provide breathing air in the 
case of ejection. Since the emergency oxygen system in the F-22 was identified as an adequate 
back-up in the event of OBOGS shutdown, it is essential that the pilot can easily and rapidly 
activate the EOS. This is critical as OBOGS shutdowns require rapid activation of the EOS and 
is especially critical in rapid decompression situations. As originally designed, the EOS was 
determined to be difficult to activate due to the small ring size of the activation handle, high 
activation forces required to pull the handle, and a two-step activation process. EOS activation 
proved to be even more difficult when the pilot is wearing winter flying gear. In addition to 
these difficulties, once activated, the EOS provides inadequate positive feedback of successful 
activation to the pilot. 

Shown above is the current modification of the EOS handle to make it easier to locate 
and pull in high-stress situations. This modification is currently being installed into the F-22 
fleet. 



ECS Modeling and Simulation 

Major F-22 systems were included in the F-22 Vehicle System Simulator program. The 
program had dedicated hardware and/or software systems in the loop and extensive 



19 



instrumentation identical to the systems in the test aircraft. However, the ECS and oxygen 
generation system were not included in the F-22 Vehicle System Simulator program due to 
budgetary constraints. 1 

The F-22 operational life support system and the thermal management system are highly 
integrated with the ram air and bleed air systems of the aircraft. The complexity of the systems 
required to meet the demands for breathable air and electronics cooling in a rapidly changing 
environment of temperature, static and dynamic pressure, and aircraft acceleration has resulted in 
highly instrumented flight tests being the only recourse for end-to-end system performance 
testing and diagnostic data gathering. The presence of the human as an integral element of the 
platform performance, depending critically on the breathable air system, adds a major degree of 
complexity and source of variance in evaluating system performance, particularly when there 
may be contaminants present in the air system. 

Computational fluid dynamics and other modeling techniques have shown significant 
potential for tools to model the F-22 systems. When components of a system were judged to be 
too complicated to model mathematically, hardware-in-the-loop testing has been an accepted 
method in the aerospace industry for over sixty years, when it was essential to verify the 
predicted performance of the sub-system before flight tests. Certain elements of the OBOGS 
might fall into this category in describing the performance of the molecular sieve in the presence 
of wide pressure fluctuations and contaminated air. Producing the proper environmental 
conditions on the ground to properly conduct an end-to-end test of the system will be a major 
challenge, but in the long run should be significantly more cost effective than relying only on 
flight test data. 

Individual elements of the F-22 life support systems have been modeled with varying 
degrees of fidelity, but there has been no complete end-to-end modeling of the system either 
statically or dynamically over the full range of experienced flight conditions. This results in an 
inadequate database to predict or trouble-shoot anomalies in system performance. The 
combination of highly instrumented flight tests and end-to-end breathing, environmental control, 
and electronics cooling system ground testing with integrated hardware-in-the-loop system 
simulation capability would give an important degree of assurance of F-22 system performance 
and form the evaluation and test basis for the next generation of aircraft. 

Existing models of environmental control/thermal management systems are proprietary 
steady-state models that are limited to mission point performance analysis. Dynamic and 
transient modeling of thermal components is required to conduct time-domain, continuous 
mission, thermo-analysis of steady-state and transient behavior to optimize the next generation 
aircraft environment control/thermal management systems. A key aspect of the development of 
this capability is a toolset that is open source. The Air Force Research Laboratory has developed 
a toolset that includes a library of physics-based models of system and sub-system components 
and a library of fluid properties and data capable of supporting the development of the dynamic 
numerical models and simulation of system transient behavior. 



1 Javorsek, D., et. al. "F-22 All Weather Fighter: Recent ECS Testing Results." 



20 



At the present time, no comprehensive numerical model can describe the physiologic 
consequences of changes in operating conditions and the performance of life support systems 
employed in modern high-performance aircraft. Several tentative computer models of 
components required to implement an integrated model of the pilot's breathing system have been 
created, but a fully validated model does not exist. 2 ' 3 Such a model could be used to simulate the 
function of the hardware and the pilot's physiological and cognitive response to environmental 
changes. Although existing physiological response data may be adequate for the development 
and validation of such an integrated model, existing data describing the effects of the reduced 
oxygen and high aircraft acceleration on the pilot's cognitive ability remain inadequate for the 
development. 



2 Bomar, J., et. al. "Modeling Respiratory Gas Dynamics in the Aviator's Breathing System 
(AL/CF-TR-1994-0047-Vol. 1)." 

3 Bomar, J. "Modeling PBA Gas Dynamics." 



21 



Safety Critical Function 



Safety Critical Function (SCF) 
A function which, if performed 
incorrectly or not performed, may 
result in death, loss of system (air 
vehicle), severe injury, severe 
occupational illness, or major 
system damage 



Safety Critical Item (SCI) 
Any Safety Significant Item whose 
failure alone may result in death 
or loss of system (air vehicle) 



Safety Significant Item (SSI) 
An item which contributes to a 
Safety Critical Function 

Back Up ~ SSI No Back Up ~ SCI 



The Safety Critical Function process 4 for the F-22 program was created as a process tool 
for the program to use to identify the safety criticality of both hardware and software items on 
the aircraft. The complexity and fully integrated nature of the F-22 demanded an extensive 
process because hardware and software issues are highly likely to impact several other systems 
and subsystems. The process involves a thorough review of literally hundreds of 
systems/subsy stems to determine criticality. 

At the F-22 EMD decision in 1991, a government and contractor team determined which 
systems/subsy stems would be classified as "safety critical" and "safety significant." The safety 
definitions on the right side of the above slide were used during this classification. Adequate 
oxygen supply to the pilot was designated Safety Critical Function 18 (SCF- 18). A safety 
critical function is a function which, if not performed or performed incorrectly, may result in the 
consequences listed above. 

The basic difference between a Safety Critical Item (SCI) and a Safety Significant Item 
(SSI) is the degree of back-up capability. Failure of a SCI alone may result in unacceptable 



4 Lockheed Martin Aeronautical Systems Company. "F-22 Post EMD Safety Critical 
Functions/Safety Significant Items/Safety Critical Items Listing." 





22 



consequences. Said another way, SCIs have no back-up. At this time, OBOGS, the BOS, and 
the EOS were considered "safety significant" because they had back-up capability — each backed 
up the other. The decision to classify the OBOGS as an SSI had a profound effect on the priority 
and oversight of the system. 



23 



Safety Critical Function 





Safety Critical Function (SCF) 
A function which, if performed 
incorrectly or not performed, may 
result in death, loss of system (air 
vehicle), severe injury, severe 
occupational illness, or major 
system damage 

Safety Critical Item (SCI) 
Any Safety Significant Item whose 
failure alone may result in death 
or loss of system (air vehicle) 

Safety Significant Item (SSI) 
An item which contributes to a 
Safety Critical Function 



Back Up ~ SSI 



No Back Up ~ SCI 



In moving from the fly-off competition into EMD, the F-22 became too heavy to be able 
to meet some of its Key Performance Parameters. Therefore, the F-22 SPO initiated a 
comprehensive aircraft weight reduction program. In April 1992, as part of the weight reduction 
effort, the Life Support System IPT study recommended BOS removal as the EOS was 
considered an adequate back-up to OBOGS. The AOG Study Panel understands this 
recommendation was based substantially on the knowledge that the ECS IPT would recommend 
that an ACM bypass conduit be installed to insure that the OBOGS would always have positive 
pressure to the inlet valve. However, that bypass conduit was never installed. 

The LSS IPT recommendation was implemented via F-22 Air Vehicle Design Directive 
033 in early 1992. 



24 



Assessment - Human Engineering 
F-22 Oxygen Scheduling 



Rapid incapae"' 1 





2SOO SOOO 7SOO I0OOO 12S0O ISOOO 17500 20000 22500 
250O SOOO 7SOO 26SOO JL500 36SOO J21O0 SOOOO 60000 

Cabin Altitude [Post R.-DJ (ft) 
Ambient Altitude IftJ 



27500 3OO0O 325O0 



F-22 Oxygen Scheduling 

The above slide integrates three key aspects of flight physiology and F-22 OBOGS 
production schedules: 

1 . Depicted across the "X" axis and moving to the right and up are the oxygen partial 
pressures and percentages that support three conditions of human performance as the 
aircraft's and cockpit altitudes increase: Normal (green-shaded region), Hypoxia 
Symptoms (yellow-shaded region), and Rapid Incapacitation (red-shaded region). 

2. Shown half-way up the "Y" axis and continuing up and right is the designed 
performance of the F-22 OBOGS in terms of the percentage of oxygen required in the 
Auto Mode or in the Max Mode. 

3. The third aspect depicts the safety lines, or level of oxygen that should be produced in 
order to ensure an acceptable amount of reserve oxygen to provide a crew member 
adequate time to activate the emergency oxygen equipment before becoming 
incapacitated. There are two lines depicted: (1) the red line shows the Alveolar Gas 
Equation which is accepted by the aviation physiology community as the minimum 
percentage of oxygen in the breathing air at various altitudes; and (2) the orange line 
is the "Warning Band" that will illuminate the OBOGS ICAWS light should the 
OBOGS oxygen production percentage not meet the required levels. 

Should the F-22 cockpit suffer a rapid loss of cabin pressurization, the required amount 
of oxygen provided to the pilot at the time of that depressurization should be 55% (as indicated 



25 



by the red line at approximately 35,000 feet), but the OBOGS warning band is set for 45% 
(orange line/vertical black arrow intersection) which is the lowest acceptable number associated 
with the satisfactory capability of the OBOGS machine. 

As depicted in the above slide, such a rapid decompression immediately puts the crew 
member at risk without an automatic activation of an emergency oxygen supply, even though the 
OBOGS may be producing enough oxygen to keep the "OBOGS Fail" ICAWS from 
illuminating. It should be noted that, despite the fact that the F-22 has never experienced a rapid 
decompression in its operational history, the margin of safety should such an event occur due to 
combat damage or system failure requires the Air Force to ensure both the "warning band" be 
adjusted to the alveolar gas equation schedule and the status of the aircraft's oxygen production 
be known to the pilot. 



26 



Outline 




■ Introduction 




■ Assessments 




■ Engineering 




■ Human Effectiveness 




■ Policies, Processes & Procedures 




■ Return to Fly 




■ Findings 




■ Recommendations 




■ Transition Operations 




■ Summary 







The second major area assessed was human effectiveness. This involved the designs of 
the F-22 ECS/LSS and how well the resultant systems contributed to the effectiveness of the 
crews operating the F-22. The following areas will be covered: 

• Human Systems Integration (HSI) and the F-22 ECS/LSS design. 

• Examples of in-flight data collected from ECS shutdowns, G-induced pilot oxygen 
saturation reductions, and hypoxia incidents (including pulse oximeter data). 

• Characterization of chemicals on the F-22 and their potential effects on crew. 

Human Systems Integration, the F-22 Program, and the Design of the F-22 ECS/LSS 

During the early Advanced Tactical Fighter (ATF) development program, the precursor 
of the F-22 development, HSI analysts were chartered to focus on Manpower, Personnel, 
Training, and Safety. From 1989 to 1994, analysts from the Aeronautical Systems Division 
(ASD) HSI Office were collocated to the ATF Program Office. As a consequence of a 
heightened awareness of the manpower, usability, maintainability, safety, human effectiveness, 
and cost savings achievable by the application of human factor engineering methods, the analysts 
and program leadership were able to bring about changes representing different priorities and 
policies in program management decision-making. Engineering, human factors, manpower, 
personnel, training, and logistics were integrated. 

Technical support of the efforts beyond the HSI technical capabilities embedded within 
the ATF Program Office came from the Air Force laboratories and the ASD engineering offices 



27 



in areas including: crew systems, life support systems, oxygen generation, propulsion, workload 
management, training methods and simulators, cockpit controls and displays, and human factors 
engineering. As a result of the ATF contract efforts, the F-22 pilot was given advanced personal 
protective equipment; integrated sensors, controls and displays; stealth technology; and sustained 
supersonic cruise. 

As the ATF moved beyond the fly-off phase and into the F-22 EMD phase, 
the acquisition policies had changed, diminishing the influence of proven military standards as 
well as national and international standards. Additionally, the workforce was downsized in 
response to acquisition reform initiatives. During the early 1990s, the ASD HSI Office manning 
was reduced to 21 positions. In 1994, prior to the developmental flight tests of the F-22, the HSI 
program office was disbanded due to funding and personnel reductions within ASD. The 
expertise required to perform the critical integration analyses became insufficient. 

Further, as a cost savings decision in the 2001 timeframe, the F-22 SPO chose to 
terminate the contractor developed life support ensemble, in favor of the government developed 
life support equipment developed as a part of the "Combat Edge" ensemble. In view of the fact 
that the Combat Edge ensemble had been certified, specialized, end-to-end testing of that 
equipment for the F-22 was not deemed necessary. 

The data depicted in the following charts indicate some anomalies in the performance of 
the F-22 oxygen and anti-G delivery systems when the ECS system cuts back or shuts down 
in-flight, or during the onset of High-G forces, which merit further analysis and testing. 

Note: The areas of Human Systems Integration (HSI) and the F-22 ECS/LSS design 
(including the evolution of the USAF HSI enterprise as applied to the F-22 program) are 
presented in greater detail in Appendix D of this report. 



28 



Assessment - Human Effectiveness 
ECS Shutdown / 2 Reduction - Msn 1051 




■■ -. 




Accelerate & climb 
from 45K to 55K 

Thrust from 
afterburner to 75% 

Inlet, outlet 
pressure & 2 
production reduced 
to below 40% 

Loss of 2 for 18 
seconds 

ICAWS illuminated 



36 sec 



Time (Zulu 



Example In-Flight Data 

The slide above 5 and the following slide depict representative useful data gathered during 
the test sorties flown as a result of direction provided by the SIB or suggestions from the AOG 
Study Panel from April- September 2011. In the above slide, the information collected came 
from the normal aircraft integrity data, which then informed both the SIB and the AOG Study 
Panel with regard to sensors to be installed for the dynamic in-flight testing to be done in the 
summer of 2011. 

In the above slide, the upper graph displays aircraft altitude versus time with each time 
sequence equating to 36 seconds. The second graph depicts the throttle setting (percent, teal 
line), the inlet pressure at the OBOGS (psi, blue line), and the outlet pressure of the OBOGS 
(psi, green line). The third graph displays the number of "Gs" being pulled by the aircraft (blue 
line) and the final graph depicts the percentage of oxygen being produced by the OBOGS (blue 
line) as well as the oxygen warning band (percent of O2, green line). 



5 The vertical axis on the second graph is in percent of military thrust requested (teal line) and 
OBOGS inlet (blue line) and outlet pressure (green line) in psi. The vertical axis on the third 
graph reflects the number of Gs normal acceleration (blue line) or the G-suit input pressure 
(green line) in psi. The vertical axis on the last graph depicts the OBOGS output 2 
percentage (blue line) as well as the OBOGS 2 percentage warning band (green line). 



29 



While the ECS rollback or shutdown at high altitudes and low power settings is an 
infrequent event, the F-22 SPO is developing a software update that should reduce the number of 
events in the future. 



30 



Assessment - Human Effectiveness 
G-induced Q 2 Reduction - Msn 1072 




02 Aug 



TST 1072 BFM - Baseline 
Altitude 




18,35 18,36 18.37 18.38 18.39 18.4 18.41 18.42 18.43 
LEFT ENGINE THRUST REQUEST 



150 
100 

































18.35 18.36 18.37 18.38 18.39 

G-Suit Input Pre 


8.4 18 

ssure 


41 18.42 18.43 




Accomplished a series 
of high-G maneuvers 
from 30Kto 10K 

Power from idle to max 



At 8 Gs, 2 production is 
reduced sequentially to 
between 60-70% 



18.35 18.36 18.37 18.38 18.39 18.4 18.41 18.42 18.43 

Time (Zulu) 



On the above slide, 6 using the same methodology of Altitude, Power, and OBOGS Inlet 
and Outlet pressures as on the previous slide, it can be seen that as the aircraft descends and the 
pilot puts eight Gs on the aircraft (blue line, third graph), the percentage of oxygen (blue line, 
last graph) produced by the OBOGS is reduced. As the pilot reduces the G load, the OBOGS 
begins to recover and then the percentage of oxygen produced by the OBOGS is reduced again 
when the pilot reapplies the Gs. 

Note that at the altitudes for this test sortie, the OBOGS O2 percentage warning band (last 
graph, green line) is quite low and is never breached, even though the amount of oxygen being 
produced does decrease to between 60% and 70%. 



6 The vertical axis on the second graph is in both percent of military thrust (magenta line) and 
OBOGS inlet and outlet pressure (blue and green lines) in pounds per square inch (psi), and 
the BRAG valve pressure (teal) in psi. The vertical axis on the third graph reflects the 
number of Gs of normal acceleration (blue line) and the G-suit input pressure (green line) in 
psi. The vertical axis on the last graph depicts the OBOGS output 2 percentage (blue line) 
as well as the 2 percentage warning band (green line). 



31 



Assessment - Human Effectiveness 
Hypoxia Incidents 



Aircraft #060, Langley, 20 Oct 11 




I I I 

Aircraft #184, Langley, 14 Dec 11 






i i i 









2000 3000 4000 

Time (seconds) 




Oxygen 

desaturizations 
during climbout 

Immediate relief 
upon using EOS 

Follow-on desats 
when EOS 
depleted 



RED - Oxygen Saturation 
BLUE - Heart Rate 



The data on the above slide serve to illustrate the utility of the fingertip pulse oximeter 
during return-to-flight operations. In the first example, the initial measurements are considered 
an "artifact" or illegitimate reading due to poor contact of the instrument with the fingertip while 
outside the aircraft. During climb-out, the pilot experiences hypoxia symptoms and observes a 
lowered oxygen saturation (red line) reading from the pulse oximeter. Upon EOS activation, the 
oxygen saturation rapidly returns to baseline where it remains until the EOS is depleted. Once 
oxygen from the EOS is depleted, there is another desaturation that is corrected upon landing and 
breathing cockpit air. The recording from the second aircraft demonstrates a similar course of 
events. 

A more stable and reliable helmet-mounted pulse oximeter is in development for use in 
the F-22 (and perhaps other aircraft). 



32 



Assessment - Human Effectiveness 
Characterization of Chemicals on the F-22 




Examples of Chemical Classes 
Assessed 

■ Alkanes/Alkenes/Alkynes 

■ Alcohols/Aldehydes 

■ Dienes/Esters/Ketones 

■ Organic Sulfur/Phosphorus 
compounds 

■ Total volatile organic 
compounds 

■ Other gases (e.g., CO, C0 2 , 
N 2 , Ar) 



759 Chemicals Assessed* 

■ 432 could potentially be 
found in the ECS 

■ 208 compounds are 
potential CNS** toxicants 

■ 126 detected to date 
during aircraft ground 
and flight testing 

■ Assessment ongoing 

'Molecular Characterization Matrix - Assessment 
**CNS - Central Nervous System 



Detected contaminants below published harmful levels, but the 
role of unmeasured chemicals remains to be determined. 



One of the two working hypotheses proposed for this Study addresses the potential for 
F-22 flight safety being compromised by the presence of toxic levels of contaminants in the air 
delivered from the OBOGS to the pilot. The presence of high levels of certain classes of 
chemicals present in jet fuel, jet oil, hydraulic fluid or their pyrolysis products could be a 
contributing factor in central nervous system (or respiratory) symptoms experienced by pilots 
and ground crew personnel. 

An extensive, multi-step, multi-disciplinary effort was undertaken by personnel from the 
USAF, Boeing, Lockheed Martin, and other consultants to identify chemicals that might possibly 
enter a pilot's breathing air on the F-22 and account for acute central nervous system (CNS) 
effects. The process, termed the Molecular Characterization Matrix (MCM), began with the 
generation of a list of chemicals known to be present in jet fuel, oil, and hydraulic fluids used on 
the F-22, together with selected chemicals believed to be associated with the pyrolysis or 
degeneration of these petroleum products. The focus was on chemicals, gases, or aerosols whose 
presence in LSS air was considered plausible by virtue of normal operation of the jet engine, or 
from leaks in seals, valves, or other conduits, or from erosion or out gassing of aircraft coatings. 
A list of example chemical classes of concern is shown on the chart above. As of January 24, 
2012, 759 chemicals associated with the F-22 have been assessed (see Appendix B of this report 
for an expanded description of this process and specific chemicals characterized). 

Based on analysis of available data, the AOG Study Panel concludes that trace levels of 
volatile organic chemicals are commonly present in the breathing air supplied by the OBOGS 
used in the F-22. The origin of these contaminants in the breathing air can be traced to their 
presence in atmospheric air and to leaks of small quantities of jet fuel, oil, or hydraulic fluid into 



33 



the ECS of the aircraft. In flight tests and ground tests, neither the level of any single chemical 
contaminant nor the sum of the concentrations of all the contaminants detected reached a 
concentration consistent with the CNS symptoms reported in recent incidents. In addition, 
biological monitoring tests conducted on the blood and urine of incident pilots and ground 
personnel as well as test pilots were negative for exposure to hazardous levels of carbon 
monoxide or other toxic substances. The ongoing efforts to identify potential toxicants (MCM 
activities) in the F-22 and the potential for additive and synergistic toxic mechanisms should 
continue until all plausible scenarios for chemical toxicity are addressed. 

Note: See Appendix B of this report for additional background information on the MCM 
analysis process and a complete description of the neurotoxicity assessment methodology. 



34 



Outline 




■ Introduction 




■ Assessments 




■ Engineering 




■ Human Effectiveness 




■ Policies, Processes & Procedures 




■ Return to Fly 




■ Findings 




■ Recommendations 




■ Transition Operations 




■ Summary 







The third major assessment area is an examination of how policies, processes, and 
procedures affected the development of the F-22 and the OBOGs system. The F-22 acquisition 
program and the associated decision making was greatly influenced by a series of legislative, 
reform, organizational, and programmatic actions. 



35 



Assessment - Policies 
The Environment 

■ USAF Acquisition workforce reduced 40% between 1992 and 2005 

■ In implementing Goldwater-Nichols, AF significantly altered its 
organizational relationships in its systems development structure 

■ Air Force, with Acquisition Lightning Bolts, transitioned significant 
development and sustainment activities to major defense contractors 

■ COTS, NDI, FAR Part 12, TSPR, TSSR, deleted Mil Standards & Mil 
Specifications 

■ AFMC & AFRL Drawdown 

■ Reduced Human Effectiveness funding and manpower -40% 

■ Moved focus away from aviation physiology, oxygen generation, 
altitude protection and occupational toxicology specialties 

■ Core competencies and personnel development suffered 

■ Systems Engineering, Human Systems Integration, Cost Estimating, 
Safety, Airworthiness, Readiness/Reliability, and Risk Assessment 
disciplines degraded 

■ Ability to fulfill "Inherent Government Responsibilities" affected 




The F-22 was developed during a period of substantial change within the Air Force 
acquisition community. From 1992 to 2005, the USAF acquisition workforce was reduced by 
40%. In its implementation of the Goldwater-Nichols Act, the Air Force significantly altered its 
organizational relationships and systems development structure. For example, the Program 
Executive Officer structure that was established diminished the authorities of the Air Force 
Materiel Command (AFMC) and the AFMC Product Centers such as the Aeronautical Systems 
Center. 

In the early 1990s, the Air Force implemented the use of "Acquisition Lightning Bolts," a 
series of reforms and efficiency initiatives that included transitioning significant development 
and sustainment activities to major defense contractors. These reforms also contained a number 
of process efficiency initiatives which included direction to make greater use of commercial off 
the shelf equipment, non-developmental items, and to take greater advantage of provisions of the 
Federal Acquisition Regulation Part 12 (e.g., commercial like acquisition, more rapid processes, 
and fewer rules). Additionally, military standards and military specifications were deleted. 

Part of the acquisition workforce drawdown involved a major reorganization of the Air 
Force Science and Technology (S&T) establishment. On October 1, 1987, the Air Force 
disestablished the four separate laboratories within AFMC (Phillips Laboratory, Wright 
Laboratory, Rome Laboratory, and Armstrong Laboratory) and formed the Air Force Research 
Laboratory (AFRL). The Armstrong Laboratory had been the S&T organization responsible for 
aviation physiology, oxygen generation, altitude protection, and occupational toxicology 
specialties. A major rationale for this reorganization was to achieve efficiencies through 



36 



consolidation. Funding for the Human Effectiveness Directorate (which had been formed from 
the Armstrong Laboratory) was reduced by 39.7% and the manning cut by 44% in the Fiscal 
Year (FY) 1999 and FY 2000 budgets. Additionally, AFRL's Defense Health Program funding 
(a part of DoD Major Force Program 8) was also withdrawn to become more closely aligned 
with purely medical applications. AFRL henceforth was funded strictly with S&T funds 
(Program 6). 

In a sense, this created the beginnings of a "perfect storm," wherein these critical areas 
were reduced from both directions (personnel and funding). It was not so much that the original 
concept of capturing efficiencies via reorganization was flawed, rather that one of the 
consequences in execution resulted in a dramatic disinvestment from what heretofore had been 
critical core mandates for a world class Air Force. 

During the course of this Study, the Study Panel conducted numerous interviews with Air 
Force acquisition personnel regarding the effect of the acquisition workforce drawdown. It was 
the consensus of these individuals that these reductions had the effect of degrading Air Force 
capabilities in certain critical disciplines such as systems engineering, human systems 
integration, safety, air worthiness and reliability, and risk assessment. Moreover, the workload 
involved in managing today's complex acquisition programs was generally thought to have 
increased. This reality, combined with fewer professionals to accomplish the increased work, 
has resulted in less time for personnel professional development (e.g., individual technical and 
managerial competencies). 

One could argue that the net effect of these environmental factors was that the Air Force 
acquisition community's capability to perform its "inherently government functions" has been 
negatively affected. It also should be noted that there is no government consensus on what those 
inherently government functions are. 

Note: A more detailed account of the evolution of the Air Force HSI Program (including 
the effects of funding and personnel changes) is contained in Appendix E of this report. 



37 



Assessment - Policies 
Process Implications 

■ Air Force acquisition and sustainment processes 
related to HSI, safety, and systems engineering 
changed dramatically 

■ Air Breathing Standards are based on 1988 Multi-National and 
OSHA standards because DOD standards were no longer being 
maintained 

■ Failure Mode Effect and Criticality Analysis last updated in 1980 
and rescinded in 1998 

■ Determination of Safety Critical Items problematic 

■ IPTs were given decision authority unless dealing with 
significant integration/interdependence issues 

■ AF Human Systems Integration plan not fully implemented 




In addition to the substantial organizational changes and resource reductions, Air Force 
acquisition and sustainment processes have also changed dramatically over the past two decades. 
This is especially true with respect to human systems integration, safety, and systems 
engineering. For example, as previously mentioned, military standards and military 
specifications, which in the past had provided clear direction to the contractors, were deleted as 
part of acquisition reform. Over the years, air breathing standards had been developed as part of 
a multi-national process, originally by the Air Standardization Coordinating Committee (ASCC), 
which consisted of representatives from Great Britain, Canada, Australia, New Zealand, and the 
United States, and later the Air and Space Interoperability Council (ASIC). These standards and 
guidance documents were supplemented by United States standards, which were later deleted as 
an efficiency measure. 

The multi-national air breathing standards and advisory publications, which guided US 
aircraft development (including the F-22), were the 1988 ASIC Advisory Publication 61/101/10 
and ASCC Publication 61/101/6A. The 1988 Advisory Publication 61/101/10 was recently 
updated (October 2010) and issued as ASIC Advisory Publication 4060. This update included a 
substantially more extensive list of contaminants, as well as data on oxygen scheduling for 
aircraft operating above 50,000 feet. However, it is important to note that these documents 
constitute only advisory guidance to industry. As of this writing, the Study Panel understands 
that as a result of this SAB Study and the Safety Investigation Board examination of the F-22 
hypoxia-like events and the OBOGS, the Assistant Secretary of the Air Force (Acquisition) has 
directed that AFMC (via AFRL) develop a comprehensive directive regarding OBOGS that 
would constitute direction to contractors in the development of Air Force aircraft systems. 



38 



While the standard will initially be only directive on the Air Force, it is anticipated that this 
would become the basis for a DoD directive. 

The document which describes the conduct of the Failure Mode Effects and Criticality 
Analysis (FMECA) process was last updated in 1980 and rescinded in 1994. In examining the 
use of FMECA in developing the F-22, it is of interest to note that the F-22 OBOGS is a "fly to 
warn/fail system" and hence periodic inspection and maintenance schedules for the OBOGS 
were not specified. While the F-22 underwent several criticality analyses, it is not clear that the 
implications of adopting the fly to warn/fail philosophy were fully considered. (Note: The 
aircraft will also generate maintenance Fault Reporting Codes when the OBOGS malfunctions. 
These are recorded on the Data Transfer Cartridge that is downloaded after each flight.) 

As discussed earlier in this report, the determination of Safety Critical Items was 
problematic. The Back-up Oxygen System was deleted in a major weight reduction exercise as 
the F-22 entering EMD was too heavy to meet requirements. The rationale was that if the 
OBOGS failed or malfunctioned, the Emergency Oxygen System was believed to be an 
acceptable back-up. As the EOS at F-22 operating altitudes provides only 5-20 minutes of 
usable oxygen, it is highly questionable as to whether the EOS was an acceptable back-up. 

As modern acquisition programs were becoming increasingly complex and integrated, in 
the early 1990s the Air Force adopted the concept of Integrated Product Teams to manage the 
acquisition of systems and subsystems. These IPTs were given broad authority for technical, 
financial, and contractual decisions, unless the issues in question involved significant integration 
and interdependence decisions. In those cases, those decisions were handled at a higher level. 

Regarding human systems integration, the Air Force efforts to implement an effective 
HSI program has been characterized by fits and starts over the last three decades. The Air Force 
first initiated actions in 1985 in response to a 1981 Government Accountability Office report and 
a Defense Science Board report, which identified a need for centralized control of manpower, 
personnel, and training (MPT) factors in the acquisition of weapon systems. At this same time, 
Congress required MPT to be identified at Milestones 1 & 2. (Note: "MPT factors" was the 
original terminology used to describe what is now known as HSI.) 

A prototype organization was established in 1988 at the Aeronautical Systems Center 
(ASC) to handle the consideration of MPT factors early in the acquisition of major weapon 
systems. HSI analysts were assigned to support the F-22 systems engineering and development 
efforts. At that time, the term MPT analyses had been changed to HSI. However, the HSI office 
staff at ASC was reduced in the early 1990s due to manpower reductions and then disbanded in 
1994. 

In 1994, the AFMC Director of Requirements approved movement of HSI responsibility 
to the Human Systems Center (HSC). To make up for what was perceived as a critical HSI 
shortfall, an HSI cadre was established and initially funded by the Air Force Materiel Command 
in 1995 to train, advise, and provide consultation to AFMC organizations. The funding and 
personnel positions were lost in subsequent years, as HSI was never fully embraced into the 



39 



acquisition process. In 2004, an Air Force Scientific Advisory Board study 7 recommended that 
the Air Force adopt proven HSI best practices. The Air Force Surgeon General (AF/SG), 
recognizing the need and the medical community's role for portions of HSI, restored 31 
manpower positions and funding at HSC in 2006. The HSI program was transferred to the Air 
Force Research Laboratory at Wright-Patterson AFB when the HSC was disestablished in 2008. 
In 201 1, a new HSI Implementation Plan was approved by the AFMC Commander. The AF/SG 
provided funding for 3 1 personnel positions with an agreement that this would be a temporary 
cost share with line funding to be provided in the future. Currently, this plan is not fully funded 
beyond the Program 8 funding provided by AF/SG and a relatively small amount of Research, 
Development, Test, and Evaluation funds and Operations and Maintenance funds. The Study 
Panel understands that additional line funding is expected in FY 13 to complete the AFMC HSI 
Implementation Plan. 

Note: As previously mentioned, a more detailed account of the evolution of the Air Force 
HSI Program (including the effects of funding and personnel changes) is contained in Appendix 
E of this report. 



7 Erickson, J., & Zacharias, G. "Report on Human-System Integration in Air Force Weapon 
Systems Development and Acquisition (SAB-TR-04-04)." 



40 



Assessment - Policies 
F-22 Program Implications 

■ F-22 first major post-Goldwater-Nichols Air Force 
aircraft acquisition program 

■ The F-22 was touted as the model for Acquisition 
Reform 

■ Capabilities-Based Requirements 

■ Performance-Based Contracting 

■ Extensive use of IPTs--decentralized decision making 

■ Cost caps on EMD and production 

■ Multiple program restructures 

■ Significant F-22 Program Office reductions 

Impacts of complex, modern "integrated" system 
versus legacy "federated" system 




As mentioned, the implementation of these various reforms, organizational, and 
programmatic actions had far reaching implications for the F-22 and the OBOGS sub-system. 

It is important to note that the F-22 was the first major aircraft program in the post 
Goldwater-Nichols era. The program was considered to be a model for a series of improvements 
known as Acquisition Reform, as the F-22 SPO adopted much of the philosophy, principles, and 
processes of this reform initiative. 

In the area of requirements, the Air Force adopted capability based requirements which 
involved changing from performance-oriented specifications (altitude, airspeed, payload) to the 
capabilities or desired effects orientation. On the contracting side, acquisitions and the resulting 
contracts were to be structured around results as opposed to stipulating how the work was to be 
performed. 

Because of the size and complexity of the F-22 program, it was realized early on that 
delegating decision making would be critical. Accordingly, the F-22 SPO enthusiastically 
adopted the IPT concept and delegated substantial authority for technical, contractual, and 
financial decisions. It should be noted that the Life Support Systems IPT conducted the study 
which ultimately recommended that the BOS be removed and a separate Environmental Control 
System IPT evaluated the merits of installing an ACM by-pass. 

The F-22 has been subjected to numerous cost caps on EMD and production. The FY98 
the National Defense Authorization Act capped the EMD program at $18,688 billion (B) and 
production at $43.34B. This program has also seen numerous restructures. There were funding 
reductions in FYs 1993, 94, 95, and 96. There have also been several production caps at 



41 



acquisition milestones as a result of major defense reviews or as part of Program Budget 
Decisions (PBDs) which progressively reduced the production: 



• Milestone I, 750 aircraft 

• Milestone II, 648 aircraft 

• Bottom-Up Review, 442 aircraft 

• Quadrennial Defense Review, 339 aircraft 

• Office of the Secretary of Defense PBD 753, 186 aircraft 

A diagram which depicts F-22 program key milestones and production caps is included in 
Appendix F of this report. 

As the Air Force acquisition workforce was being reduced, so was the manning in the 
F-22 System Program Office. In 1992, the SPO was authorized 350 manpower spaces, today the 
authorization totals 180. 

To summarize, the F-22 has been developed during a remarkable period of 
organizational, process, and programmatic change. These changes are compounded by the basic 
fact that the F-22 is the first fighter that has been acquired from the start as an integrated system 
as opposed to a federated or vertical development which had characterized past aircraft 
acquisitions. This integrated approach introduced an extraordinary system of systems 
complexities and interoperability challenges, which were compounded by rapid evolution of 
information technology — these challenges will continue going forward, resulting in significant 
implications for follow on aircraft development. 



42 



Section 3: Return to Fly 



Outline 




■ Introduction 




■ Assessments 




■ Fnninpprinn 

■ lull Ivvl II IU 




■ Human Effectiveness 




■ Policy, Processes & Procedures 




■ Return to Fly 




■ Findings 




■ Recommendations 




■ Transition Operations 




■ Summary 







The SAB, in concert with the SIB members and the ACC/SPO Team, was challenged 
with defining the necessary criteria to return the F-22 to flight status. The following slides 
provide a discussion of how that process was conducted and the results. 



43 



Flight Operations 
"Return to Fly" Assessment 

■ "Protect the crews and continue to gather data" 

■ Establish a "Task Force Team" (led by ACC) 

■ Establish the 711 th HPW as the data analysis/repository 

■ Train the crews, maintenance specialists and flight 
surgeons/aviation physiologists/bio-environmental 
engineers 

■ Perform one-time and recurring mx inspections 

■ Pilots use C2A1 canisters and pulse oximeters 

■ Develop an 2 sensor to measure post-BRAG oxygen levels 

■ Develop and implement post-incident collection 
protocols for pilots and maintenance specialists 

■ Operations above 50K MSL authorized 




As the AOG Study Panel members reviewed the work done by the F-22 Class E SIB prior 
to the formation of the SAB Quicklook Study, they assisted in developing the methodology to 
plan and execute the test sorties. The Study Panel then evaluated the data from those sorties, 
along with the previous data that had been gathered from the ground functional tests. The 
process culminated with the AOG Study Panel being able to provide advice to the Air Force so 
that it could develop a prudent Return-to-Fly program for the F-22 fleet that focused on both 
protecting the crews and gathering data. 

The Return-to-Fly phase was established in such a way that the crews (pilots and 
maintenance technicians) would be protected and the SIB, the AOG Study Panel, and a newly 
established ACC-led Task Force would focus on gathering diagnostic data. 

Initially, the F-22 Life Support Systems Task Force approached each breathing air 
anomaly from the perspective of a post-anomaly "functional" investigation. However, over time 
the Task Force has become more oriented towards a "forensic" investigation with regard to 
inspection of the F-22's entire life support system. 

To date (January 2012), the Return-to-Fly phase has flown about 7,000 sorties. There 
have been 14 Breathing Air Anomalies, of which six have occurred on the ground during engine 
runs for maintenance, along with one anomaly that occurred during preparation for a flight. 
There have been eight anomalies in the air. One was reported by a pilot that experienced a 
change in the "texture" of the air and one aircraft that had an "OBOGS Fail" ICAWS illuminate 
on climb out. Neither of these two pilots reported any hypoxia-like symptoms. Two pilots 
reported fumes, or smoke and fumes, during the flight, and experienced some light headedness or 



44 



dizziness symptoms that cleared up with the use of the EOS. Three pilots experienced classic 
hypoxia-like symptoms in-flight, below 25,000 feet. In each case, they also noted a blood 
desaturation with their pulse oximeter. In each of those cases, the symptoms resolved quickly 
when the EOS was activated and the blood saturation level returned to normal. In one case, the 
symptoms presented after flight and the pilot was treated with the use of the hyperbaric chamber. 

As of the date of this report the post flight testing, sampling, inspection, and evaluation 
protocols have not yet yielded information that could lead to a root cause(s), but two incident 
aircraft are being outfitted with an expanded set of sensors to be used in a series of follow-on 
flight test sorties. 



45 



(This Page Intentionally Left Blank) 



46 



Section 4: Findings 



Outline 




■ Introduction 




■ Assessments 




■ Engineering 




■ Human Effectiveness 




■ Policy, Processes & Procedures 




■ Return to Fly 




■ Findings 




■ Recommendations 




■ Transition Operations 




■ Summary 







The previously described Engineering, Human Effectiveness, and Policy, Processes, 
Procedures assessments, along with the data collected during the Return-to-Fly activities, led the 
Study Panel to the following nine Study Findings. It should be noted, that at the time of the SAB 
AOG Study Outbrief to the Secretary of the Air Force and Air Force Chief of Staff (January 24, 
2012), the root cause(s) has yet to be determined for the F-22 hypoxia-like incidents. However, 
the Study Panel believes the actions being implemented protect the crew, significantly robust the 
system, and will produce additional data likely to lead to identifying the root cause(s). 



47 



Finding One 



The F-22 OBOGS, BOS and EOS were not classified as 
"Safety Critical Items," 

■ Life Support System IPT eliminated BOS to save weight 

■ The Environmental Control System IPT designed an air cycle 
machine bypass to provide bleed air to the OBOGS in the event of 
an ECS shutdown 

■ The Emergency Oxygen System was deemed to be an adequate 
Backup Oxygen System 

■ The Environmental Control System IPT decided to forgo the air 
cycle machine bypass 

■ With an ECS shutdown, the pilot's breathing air is cut-off and the 
pilot is then dependent on either the Emergency Oxygen System or 
dropping the oxygen mask 

■ Interrelated and interdependent decisions were made without 
adequate cross-IPT coordination 




48 



Finding Two 



Over the past 20 years, the capabilities and expertise of the 
USAF to perform the critical function of Human Systems 
Integration (HSI) have become insufficient, leading to: 

■ The atrophy of policies/standards and research & development 
expertise with respect to the integrity of the life support system, 
altitude physiology, and aviation occupational health & safety 

■ Inadequate research, knowledge and experience for the unique 
operating environment of the F-22, including routine operations 
above 50,000 ft 

■ Limited understanding of the aviation physiology implications of 
accepting a maximum 93-94% oxygen level instead of the 99+% 
previously required 

■ Specified multi-national air standards, but deleted the BOS and did 
not integrate an automated EOS activation system 

■ AFMC & AFRL core competencies were diminished due to de- 
emphasis and reduced workforce to near zero in some domains 




49 



Finding Three 



Modeling, simulation and integrated hardware-in-the-loop 
testing to support the development of the F-22 life 
support system and thermal management system were 
insufficient to provide an "end to end" assessment of the 
range of conditions likely to be experienced by the F-22. 

■ Engine-to-mask modeling and simulation was non-existent 

■ Dynamic response testing across the full range of simulated 
environments was not performed 

■ Statistical analysis for analyzing and predicting system 
performance/risk was not accomplished 

■ Performance of OBOGS when presented with the full range of 
contaminants in the ECS air was not evaluated 




50 



Finding Four 



The F-22 life support system lacks an automatically- 
activated supply of breathable air. 

■ ECS shutdowns are more frequent than expected and result in 
OBOGS shutdown and cessation of breathing air to the pilot 

■ The F-22 is the only OBOGS-equipped aircraft without either a BOS 
or a plenum 

■ The "OBOGS Fail" light on the ICA WS has a 12 second delay for 
low oxygen, providing inadequate warning 

■ When coupled with a rapid depressurization at the F-22's 
operational altitudes, the "Time of Useful Consciousness" can be 
extremely limited 

■ The EOS can be difficult to activate, provides inadequate feedback 
when successfully activated, and has a limited oxygen duration 




51 



Finding Five 



Contaminants identified in the ongoing Molecular 
Characterization effort have been consistently measured 
in the breathing air, but at levels far below those known to 
cause health risks or impaired performance. 

■ Contaminants that are constituents of ambient air, POL*, and 
PAO** are found throughout the life support system in ground and 
flight tests 

■ OBOGS was designed to be presented with breathable air and not 
to serve as a filter 

■ OBOGS can filter some contaminants and there is evidence it may 
concentrate others 

* POL - Petroleum, Oils and Lubricants 
** PAO - Polyalphaolefin 




52 



Finding Six 




The OBOGS was developed as a "fly-to-warn" system 
with no requirement for initial or periodic end-to-end 
certification of the breathing air, or periodic maintenance 
and inspection of key components. 

■ Engine bleed air certified "breathable" during system development 

■ OBOGS units are certified at the factory 

■ No integrated system certification 

■ No recurring Built-in Test (BIT), inspections or servicing 



53 



Finding Seven 




Given the F-22's unique operational envelope, there is 
insufficient feedback to the pilot about the Partial 
Pressure of Oxygen (PP0 2 ) in the breathing air. 

■ Single oxygen sensor well upstream of the mask 

■ 12 second delay in activating ICAWS when low PP0 2 is detected 

■ Inadequate indication of EOS activation when selected 

■ No indication of pilot oxygen saturation throughout the F-22 flight 
envelope 



54 



Finding Eight 



The F-22 has no mechanism for preventing the loss of the 
aircraft should a pilot become temporarily impaired due 
to hypoxia-like symptoms or other incapacitating events. 

■ Disorientation, task saturation and/or partial impairment from 
hypoxia could result in loss of the aircraft and possibly the pilot 




55 



Finding Nine 



The F-22 case study illustrates the importance of identifying, 
developing, and maintaining critical institutional core 
competencies. 

■ Over the last two decades, the Air Force substantially diminished 
its application of systems engineering and reduced its acquisition 
core competencies (e.g., engineering, Human Systems Integration 
(HSI), aviation physiology, cost estimation, contracting, program & 
configuration management) to comply with directed reductions in 
the acquisition work force 

■ By 2009 the Air Force had recognized this challenge and developed 
a comprehensive Acquisition Improvement Plan (AIP) and a Human 
Systems Integration plan 

■ Although the AIP has been implemented the HSI plan is early in its 
implementation 

■ A clear definition of "inherent government roles and responsibilities" is 
not apparent 




56 



Section 5: Recommendations 



■ Introduction 

■ Assessments 

■ Engineering 

■ Human Effectiveness 

■ Policy, Processes & Procedures 



■ Retur 

■ Findings 

■ Recommendations 
■ 

■ Summary 



Based on the previous Findings, the AOG Study Panel makes the following 14 
Recommendations to robust the F-22 life sustainment system. 



Outline 




Recommendations (1-2) 



1. Develop and install an automatic Backup Oxygen Supply 
(BOS) in the F-22 life support system. 

(OPR: ACC) (OCR: AFLCMC) 

■ Consider a 100% oxygen BOS capability unless hazardous levels of 
contaminants in OBOGS product air can be ruled out 

2. Re-energize the emphasis on Human Systems Integration 
throughout a weapon system's lifecycle, with much greater 
emphasis during Pre-Milestone A and during Engineering 
and Manufacturing Development phases. 
(OPR.AFMC, SAF/AQ) 

■ Reestablish the appropriate core competencies. (OPR: SAF/AQ) 
(OCR: AFMC, AF/SG) 

■ Develop the capability to research manned high altitude flight 
environments and equipment, develop appropriate standards, 
oversee contractor development and independently certify critical, 
safety-of-flight elements. (OPR: AFRL, AFLCMC) 




58 



Recommendations (3 - 4) 



3. Establish a trained medical team with standardized 
response protocols to assist safety investigators in 
determining root causes for all unexplained hypoxia- 
like incidents. (OPR: AFLCMC, AF/SG) (OCR: AFRL) 

4. Develop and implement a comprehensive Aviation 
Breathing Air Standard to be used in developing, 
certifying, fielding and maintaining all aircraft oxygen 
breathing systems. (OPR: SAF/AQ) (OCR: AFMC, 
AFRL, AFLCMC) 




59 



Recommendations (5 - 6) 



5. Create and validate a modeling and simulation 
capability to provide end-to-end assessments of life 
support and thermal management systems. (OPR: 
AFMC) 

■ The initial application should be the F-22 followed by F-35 

6. Improve the ease of activating the EOS and provide 
positive indication to the pilot of successful 
activation. (OPR: ACC) (OCR: SPO) 




60 



Recommendations (7 - 8) 



7. Complete the molecular characterization to 
determine contaminants of concern. 
(OPR: AFRL, ACC, SPO) 

■ Where appropriate alternative materials should be 
considered to replace potential sources of hazardous 
contaminants. (OPR: AF/A4/7, AFPA) 

■ Develop and install appropriate sensor and filter/catalyst 
protection. 

8. Develop and implement appropriate inspection and 
maintenance criteria for the OBOGS and life support 
system to ensure breathing air standards are 
maintained. (OPR: ACC) (OCR: SPO) 




61 



Recommendations (9-11) 



9. Add a sensor to the life support system, post-BRAG 
(Breathing Regulator/ Anti-G), which senses and 
records oxygen pressure and provides an effective 
warning to the pilot. (OPR: ACC) (OCR: SPO) 

10. Integrate pilot oxygen saturation status into a tiered 
warning capability with consideration for automatic 
Backup Oxygen System activation. (OPR: ACC) 
(OCR: AFMC) 

11. Develop and install an Automatic Ground Collision 
Avoidance System (AGCAS) in the F-22. (OPR: ACC) 
(OCR: SPO) 




62 



Recommendations (12- 14) 



12. Clearly define the "inherent governmental roles and 
responsibilities" related to acquisition processes and 
identify the core competencies necessary to execute 
those responsibilities- (OPR: SAF/AQ, SAF/FM, SAF/IE, 
AF/A4/7) 

13. Create a medical registry of F-22 personnel who are 
exposed to cabin air or OBOGS product gas and also 
initiate epidemiological and clinical studies that 
investigate the clinical features and risk factors of 
common respiratory complaints associated with the F-22. 
(OPR:AF/SG) 

14. Establish a quarterly follow-up to ensure SAB 
recommendations are implemented in a timely fashion or 
to respond to any event of significance. The SAB is 
available for continued support if desired. (OPR: HAF) 




63 



Summary 
Working Hypothesis Status 

1. The F-22 oxygen delivery system is failing to deliver adequate 
oxygen to the pilot, resulting in hypoxia symptoms that threaten 
safety of flight 

A. Episodic releases — None documented (Independent 2 sensor 
will provide additional detection capability) 

B. Low inlet pressure— YES (Mitigated by ECS Software change, 
improved EOS access and BOS addition) 

C. Failure mode in equipment from OBOGS to mask — YES (Mitigated 
by recurring inspections and independent 2 sensor) 

D. Leak or failure from bleed air valves to mask — YES (Mitigated by 
recurring inspections and independent 2 sensor) 

E. OBOGS oxygen delivery schedule and performance — YES, but 
exceeds physiological requirement (Mitigated by independent 2 
sensor) 

F. Change in tier 2/3 supplier/component materials/process — NO 




The above slide and the next give the current status of hypothesis testing as of the final 
AOG Study briefing given on January 24, 2012. 

Failure to deliver adequate O2 due to episodic releases of nitrogen was not documented 
by any of the data flights. However, the Panel was not able to close this hypothesis due to the 
low number of data flights available. Once additional flights with the additional O2 sensor are 
flown, this hypothesis should be able to be closed. 

Low inlet pressure was documented on several flights with ECS shutdowns, but this 
failure has been mitigated by improved ECS software minimizing shutdowns, improved access 
to the EOS, and addition of the BOS. 

Leaks or hardware failures in the system were documented; however, these risks were 
mitigated with improved recurring inspection and installation of the independent O2 sensor 
which will provide the pilot warning of such a failure. 

Failure of the OBOGS to deliver commanded performance was documented with 
decreases under G-loading; however, in all cases the performance was still above the warning 
band and above the demands of the pilot as dictated by cabin altitude. 

No changes in suppliers or manufacturing processes were documented. 



64 



Summary 
Working Hypothesis Status 

2. The F-22 delivery system is either producing or failing to filter a 
toxic compound(s) resulting in hypoxia-like symptoms that 
threaten safety of flight 

A. Saturation — None documented (Independent 2 sensor 
narrows causes) 

B. Episodic releases— None documented (Independent 2 sensor 
narrows causes) 

C. Failure mode in equipment from OBOGS to mask — YES 
(Mitigated by recurring inspections and C2A1 filter) 

D. Leak or failure from bleed air valves to mask — YES (Mitigated 
by recurring inspections and C2A1 filter) 

E. OBOGS oxygen delivery schedule — None documented 
(Software Deep Dive and G-drop assessment underway) 

F. Changes in tier 2/3 supplier/component material/process - NO 




No documented cases of zeolite saturation causing reduced O2 concentration were 
documented. Installation of the independent O2 sensor close to the pilot's mask will provide 
warning and additional data on this condition. 

No episodic releases of nitrogen or contaminants were documented. The independent O2 
sensor will provide warning and additional data. 

While hardware equipment failures and leaks were documented, recurring inspections, 
and the addition of the C2A1 filter mitigate the risk to the pilot while providing additional data 
on likely contaminant sources. 

No anomalies were documented in the oxygen delivery schedule; however, a software 
deep dive is still underway and a further assessment of the reasons for the drop in O2 
concentration noted under G-loads. 

No changes in suppliers or component manufacturing processes were identified. 



65 



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66 



Section 6: Transition Operations 



Outline 




■ Introduction 




■ Assessments 




■ Engineering 




■ Human E 




■ Policy, Processes & Procedures 




■ Return to Fly 




■ Findings 




■ Recommendations 




■ Transition Operations 




■ Summary 







As the Air Force continues its Return-to-Fly phase, the AOG Study Panel reviewed the 
conditions which could permit the F-22 fleet to transition from this rather manpower intensive 
phase of data collection and analysis to more "normalized" flying operations. 



67 



Transition Operations - 
Near Term 




■ Implement improved access to and ease of activation of EOS 

■ Implement an independent post-BRAG Z sensor providing 
indication, warning, and recording capability 

■ Field helmet-mounted pulse oximeter 

■ F-22 Life Support Systems Task Force should consider installing CO 
and C0 2 detectors in the F-22 cockpits 

■ F-22 Life Support Systems Task Force should consider using a 
vacuum canister during maintenance engine runs and assess the 
contents should there be an incident 

■ Leveraging the NASA or similar independent capabilities, develop 
and implement the appropriate post-incident protocols with greater 
emphasis on forensic analysis of the entire life support and cabin 
pressurization systems 

■ Analyze data gathered to determine effectiveness of the C2A1 filter 
for safety and data collection 

■ F-22 Life Support Systems Task Force and 711 HPW identify the 
need for contaminant mitigation measures for both OBOGS and 
cockpit breathing air 



The above slide depicts the actions that the AOG Study Panel believes should be taken 
and the steps that should be completed before terminating the F-22 Life Support Systems Task 
Force phase. Of note are some fairly significant assessments to be made: 

First, the F-22 Life Support Systems Task Force should consider if the Air Force should 
install reliable, relatively inexpensive, carbon monoxide (CO) and/or carbon dioxide (CO2) 
detectors in the cockpit. It is the Study Panel's view that until contamination of the ECS air can 
be completely ruled out; detecting the presence of CO and/or CO2 could aid both the pilot and 
maintenance technician. For the pilot, knowing the quality of the cockpit pressurized air could 
be very important, especially if activation of the Emergency Oxygen System will not provide 
enough oxygen to allow the aircraft to reach an appropriate landing base without descending 
below 10,000 feet. In that scenario, the Air Force may prefer for the pilot to descend to 25,000 
feet with a cabin altitude of 10,000 feet or lower, drop the oxygen mask, and breathe cockpit air. 

Secondly, for the maintenance technician who may begin to experience hypoxia-like 
symptoms on the ground while breathing cockpit air, having CO and/or CO2 detectors could 
provide an immediate indication of the quality of the cockpit air. The F-22 Life Support Systems 
Task Force should also consider requiring each maintenance technician to employ a vacuum 
(summa) canister on each ground maintenance engine run. To this point, for each of the engine 
run anomalies, the Study Panel understands that the F-22 Life Support Systems Task Force has 
been unable to obtain any data of significance once the maintenance technician has shut down 
the aircraft, opened the canopy and then had swab tests and summa canisters placed in the 
cockpit. Having the vacuum canisters present for every engine run should capture the air exactly 



68 



at the time of the occurrence. Analysis of the canister air would only be accomplished should 
there be a hypoxia-like event. Other canisters would be recycled. 

The AOG Study Panel was able to establish a relationship with members of NASA's 
Johnson Space Center who have extensive experience in evaluating and assessing oxygen 
generation systems. As a result, the Panel believes the F-22 Life Support Systems Task Force 
may be able to leverage these NASA (or other similar independent capabilities) in further 
refining their post- incident forensic analysis. 

As the data continues to be assessed and analyzed, the F-22 Life Support Systems Task 
Force should assess the effectiveness of the C2A1 filter for both safety and data collection. They 
should also bring to closure the Molecular Characterization effort to determine the need for 
developing contaminant mitigation measures. 



69 



Transition Operations - 
Long Term 




■ Install an automatically-activated Backup Oxygen 
System (BOS) 

■ Determine, through further data analysis, the need 
for aircraft mounted measurement and mitigation 
of contaminants in the breathing air 

■ Develop and install an AGCAS for the F-22 



Although more normalized operations can be achieved with the steps discussed on the 
previous slide, there are some follow-on permanent steps (install automatic BOS and Automatic 
Ground Collision Avoidance System (AGCAS), determine need for aircraft mounted 
measurement/mitigation of breathing air contaminants), that should be taken to provide the F-22 
with a more robust life support system capability to ensure mission effectiveness. 



70 



Summary 



■ Since 2008, the F-22 fleet has experienced an unacceptable number 
of unexplainable hypoxia-like events 

■ The Air Force Scientific Advisory Board and the F-22 Life Support 
Systems Task Force have not yet determined the root cause(s) of 
the incidents, but have identified and mitigated a number of risks 

■ The measures taken to protect the crews and gathering of 
appropriate data are providing substantive and valuable 
information and have narrowed the possibilities while maintaining 
combat capability 

■ Continuing the aggressive Task Force approach with all 
ECS/OBOGS anomalies will be critical in resolving the unexplained 
hypoxia-like events 

■ Implementing the Findings and Recommendations along with the 
considerations presented in the Transition Operations section 
should provide the F-22 with a significantly improved margin of 
safety and operational effectiveness 




Implementing the Recommendations and the considerations presented in the Transition 
Operations section of this report will provide the F-22 with a significantly improved margin of 
safety and operational effectiveness. 



71 



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72 



Appendix A: United States Air Force and Navy 
Aircraft Oxygen Generation (AOG) Systems 



This appendix describes the AOG systems found on most other Air Force and Navy 
aircraft. These systems are highly common in basic technology, but also exhibit several unique 
differences in design philosophy and implementation. At the end of the description for each 
weapon system, the recent history of hypoxia-like incidents is identified with emphasis on the 
unknown cause incidents where no root cause is documented. 

A.1 F-15A-D Eagle 




Figure A-l. F-15A-D Legacy Liquid Oxygen (LOX) Converter. 

The F-15A-D has retained the traditional liquid oxygen (LOX) system. This system 
(Figure A-l above) uses ground-serviced LOX (99.99% pure), which is converted to a gas before 
it is delivered to the aircrew. The system then makes use of a dilution regulator in the cockpit to 
mix the gaseous oxygen (O2) with cockpit air to achieve the appropriate partial pressure of 
oxygen for the cabin altitude. The crew has the option of selecting 100% where the breathing 



73 



gas is 100% oxygen. These systems have been in use for many years, and while they have the 
advantage of being able to provide 100% O2, they require extensive ground servicing and LOX 
production capability with the associated logistical footprint. A separate emergency oxygen 
system (EOS) is seat-mounted and can be manually activated or activated by ejecting. The unit 
size is approximately 20 x 16 x 18 inches (in). 



USAF Hypoxia Incident Rate 
per 100,000 Flight Hrs 




Figure A-2. USAF Hypoxia Rates for Selected Aircraft. 

As noted in Figure A-2 above, F-15A-D aircraft have had a low rate of hypoxia incidents 
and a very low rate of unknown cause incidents where root cause could not be identified. Most 
incidents were attributed to a mechanical system failure, hose routing, or contaminated LOX. 

A.2 F-16 Fighting Falcon (Unmodified Pre-Block 50) and F-18A/B 
Hornet 

F-16 aircraft delivered prior to 1997 were delivered with a LOX system similar to that 
used on the F-15A-D aircraft. Many of these aircraft were later retrofitted with the On-Board 
Oxygen Generation System (OBOGS) which were delivered on the new Block 50 aircraft. 

As noted for the F-15A-D, the early F-16 aircraft had a very low rate of hypoxia incidents 
and no recent unknown cause incidents. Most incidents were caused by improper routing of 
hoses which then became restricted in flight. 



74 



A.3 F-15E Strike Eagle 

The F-15E Molecular Sieve Oxygen Generation System (MSOGS), OC1093 Oxygen 
Concentrator (Figure A-3 below), supplies oxygen for crew members with the added benefit of 
supporting Pressure Breathing for Gs (PBG) regulators. The unit incorporates a rapid-cycle 
pressure-swing adsorption process, which uses two molecular sieve filled beds to generate 
oxygen enriched breathing gas on board the aircraft. These beds are packed with 13X zeolite 
held in place by positive spring pressure. The system has a 0.01 micron coalescing input filter 
designed to capture aerosols and water and a 0.1 micron output filter to retain zeolite particles. 
The unit size is approximately 13x12x18 inches. 




Figure A-3. F-15E Molecular Sieve Oxygen Generation System. 

This system also contains an integral oxygen monitor, self-test features, and a 
single-stage air-driven booster pump which charges a built-in, automatically activated back-up 
oxygen supply (BOS) with product gas. The MSOGS always operates at maximum efficiency 
producing about 93% oxygen which is then diluted by cockpit-mounted regulators. These 
CRU-98 regulators are similar to the CRU-73A regulators used in F-15A-D aircraft, except they 
have been modified to provide positive pressure breathing as a function of G-forces. Also, the 
CRU-98 is tuned to allow a slightly richer mix of the MSOGS gas with cabin because the 
MSOGS makes 93% O2 and the older LOX system provided virtually 100% oxygen. The system 



75 



has a mean time between failures (MTBF) of 2,000 hours, requires replacement of the inlet filter 
every 400 hours, and it incorporates a Built-in-Test feature. 

The F-15E has a very low hypoxia incident rate with almost no unknown cause incidents. 
Two unknown cause incidents occurred on the same aircraft. The problem was eliminated when 
the unit replaced the left engine on the recommendation of the Depot. No root cause was ever 
determined. 

A.4 F-16 Block 50, Retrofitted F-16 Aircraft 




Figure A-4. F-16 Block 50 OBOGS. 

The OBOGS system used on F-16 Block 50 aircraft (Figure A-4 above), and being 
retrofitted to earlier blocks, is very similar to the system on the F-15E. The unit incorporates a 
rapid-cycle pressure-swing adsorption process, which uses two molecular sieve filled beds to 
generate oxygen enriched breathing gas on board the aircraft. These beds are packed with 13X 
zeolite held in place by positive spring pressure. The system has a 0.01 micron coalescing input 
filter designed to capture aerosols and water and a 0.1 micron output filter to retain zeolite 
particles. Unlike the F-15E, the F-16 makes use of a 250 cubic inch plenum rather than the BOS 
on the F-15E. This plenum provides 5-6 minutes of breathing air with a system shut-down. The 
unit size is approximately 12 x 9 x 13 inches. 



76 



As noted in Figure A-2 (previous), the F-16 OBOGS system has had a higher rate of 
hypoxia incidents. The leading cause of those incidents where root cause was identified was 
hose routing, while two of the three unknown cause incidents were attributed to symptoms 
consistent with hyperventilation. 

A.5 F-18C/D/E/F/G Hornet/Growler 




Figure A-5. F-18 Oxygen Concentrator System. Note: The Oxygen Concentrator is Used 
on New Production F-18C/D/E/F/G aircraft. 

The F-18C/D/E/F/G aircraft make use of the OC1169 Oxygen Concentrator system 
(Figure A-5 above). This is twin sieve system similar in operation to the F-15E system. The two 
zeolite cylinders contain 5AMG zeolite in a packed configuration. The inlet filter is the 0.01 
micron coalescing design with the outlet filter being a 0.6 micron to protect against zeolite 
particle movement into the gas product. The system includes a 97 cubic inch plenum. The unit 
size is approximately 14 x 9 x 13 inches. 

The F-18 has experienced a significant number of hypoxia-like events over the past few 
years. The US Navy investigation of these events has attributed the majority to the pilot's 
breathing elevated levels of carbon monoxide (CO) on the carrier deck. The Navy is adding a 
catalyst filter to eliminate CO in the product gas. 



77 



A.6 AV-8B Harrier II 




Figure A-6. AV-8B Oxygen Concentrator. 

The AV-8B currently uses the OC1172 Oxygen Concentrator (Figure A-6, above). Its 
functioning is similar to that of the unit installed in the F-15E. It uses two packed 5AMG zeolite 
beds with the 0.01 micron coalescing inlet filter and the 0.1 micron outlet filter. The system also 
provides a 73 cubic inch plenum. The unit size is approximately 13x11x11 inches. 

There were no reported hypoxia-like incidents with the AV-8B. 

A.7 T-6A Texan II 

The OBOGS on the T-6A consists of the OC1132 Oxygen Concentrator (Figure A-7 
below). This concentrator consists of two beds of packed 13X zeolite with a 0.01 micron inlet 
filter and a 0.1 micron outlet filter on the zeolite beds. Its functioning is similar to that on the 
F-15E with the exception that its plenum is sized at 300 cubic inches (in). The unit size is 
approximately 13x9x10 inches. 



78 




Figure A-7. T-6A Texan II Oxygen Concentrator. 

The T-6A has had a low rate of reported hypoxia incidents. Early system reliability was 
degraded to 967 hours MTBF due to problems with a faulty slide valve and a pressure reducer. 
Recent reliability is much improved. No unknown cause incidents have been reported. 

A.8 B-1 B Lancer 

The B-1B uses conditioned bleed air to drive six canisters filled with immobilized 13X 
zeolite. The zeolite crystals are immobilized by binding with an organic polymer. These 
canisters have both inlet and outlet filters that consist of borosilicate glass fibers bonded with 
epoxy resin. The element is replaceable and removes contaminant particles from incoming bleed 
air and the breathing gas to a level of 0.6 microns. 

The oxygen system (Figure A-8 below) provides oxygen enriched gas of sufficient 
pressure to maintain crew breathing requirements at all times. Breathing gas (93% O2) is 
provided from the primary sub-subsystem, and 100% O2 from the back-up and emergency 
sub-subsystems. The back-up sub-subsystem is an alternate source of 100 percent oxygen for the 
flight crew and is ground serviced by maintenance. The unit size is approximately 16 x 24 x 18 
inches. 



79 



The B-1B has a very low reported rate of hypoxia incidents and no reported unknown 
cause incidents. 




Figure A-8. B-1B Lancer Molecular Sieve Oxygen Generation System. 



A.9 B-2A Spirit 

The B-2A Oxygen Generation and Distribution System (Figure A-9 below) uses 
conditioned bleed air to drive three canisters filled with immobilized 13X zeolite. The zeolite 
crystals are immobilized by binding with an organic polymer. These canisters have both inlet 
and outlet filters that consist of borosilicate glass fibers bonded with epoxy resin. The element is 
replaceable and removes contaminant particles from incoming bleed air and the breathing gas to 
a level of 0.6 microns. The unit size is approximately 18x15x13 inches. 

The B-2A has a very low reported rate of hypoxia incidents and no reported unknown 
cause incidents. 



80 



CT SAMPLE 

COI*IECTK*l FftOD OCT GAS OUTLET 




Figure A-9. B-2A Spirit Oxygen Generation and Distribution System. 

A.10 V-22 0sprey 

The OC1129 oxygen/nitrogen concentrator (Figure A- 10 below) performs the functions 
of two separate systems. First, it supplies oxygen-enriched air for aircrew breathing and second, 
it supplies inert gas to the fuel tanks to protect the aircraft from fuel tank explosion and fire. The 
system uses four canisters of zeolite and an integrated plenum. The unit size is approximately 16 
x 1 1 x 25 inches. 

There have been no reported hypoxia incidents in the V-22 series aircraft. 



81 




Figure A-10. V-22 Osprey Oxygen/Nitrogen Generation System. 

A.11 F-35 Lightning II 

The F-35 OBOGS (Figure A- 11 below) uses two immobilized 13X zeolite beds to 
generate the oxygen enriched breathing gas. Like the F-22 system, the F-35 controls dilution as 
a function of cabin altitude by controlling the charge-purge cycle times of the molecular sieve 
canisters. Both inlet and outlet filters protect against 0.6 micron particles. A seat-mounted BOS 
provides automatic fill-in to complement OBOGS during flight transient conditions and is 
automatically selected during ejection. This BOS obviates the need for a separate EOS. The unit 
size is approximately 16x15x5 inches. 

The F-35B has had a single hypoxia-like incident. In that incident the pilot had spent 25 
minutes breathing the exhaust (CO) of the chase aircraft sitting on the ground before takeoff. 



82 



Figure A-ll. F-35 On-Board Oxygen Generating System. 

A.12 Summary 

Table A-l (following) provides a summary of the various current USAF and USN 
OBOGS installed in their aircraft. All of these weapon systems, which leverage the OBOGS 
technology, have certain common traits: 

• They all use conditioned bleed air from the engine as the breathing gas. Conditioning 
varies by mission design series. While all use heat exchangers, the cooling fluid 
might be air or fuel or polyalphaolefm. 

• None of the systems use a catalyst or filter to explicitly filter potential contaminants 
in the bleed air; rather, they assume the bleed air is "breathable." (The F-18 is 
moving towards a catalyst to eliminate CO in the breathing air). 



83 



• All depend on Pressure Swing Adsorption process to generate enriched oxygen from 
ambient air using the ability of adsorbents (synthetic zeolitic molecular sieve) to 
absorb primarily nitrogen. 

• All systems have a Built-in-Test Feature and use a Zirconia Oxygen Sensor. 
The systems, however, have some differences in implementation: 

• Some of the canisters of zeolite are loosely "packed" and held in place by mechanical 
forces while some immobilize the zeolite in a clay or an organic polymer. 

• All of the systems, except for the F-22 implementation, include a Backup Oxygen 
System or a Plenum (reservoir) to provide some period of enriched oxygen with a 
shutdown of the OBOGS. 

• Input filters vary from an input filter that is 93% efficient at 0.01 micron to one that is 
designed to filter at the 0.6 micron level. 

• Two different types of zeolite are used. The Air Force uses a 13X zeolite while the 
USN uses a 5AMG zeolite. 

• Outlet filters range from 0.1 micron to 0.6 micron to 30 microns on the V-22. 

• With the exception of the F-22 system, all have scheduled filter replacement at about 
400 hours of operation. Several also have routine replacement of the zeolite material. 

A.13 Finding and Recommendation 

Finding: With the exception of the F-22 OBOGS, AOG systems have a proven history 
of safe, repeatable performance with robust back-up in BOS or Plenum systems. 

Recommendation: Remain wary of a rise in the rate of unknown cause hypoxia 
incidents and monitor filter status for contaminants. 



84 





Input Filter (particle)? 


Zeolite 


Immobilized 
vs Packed 


Check Valve 


Plenum/ Storage Tank 


02% Produced 


OBOGS 

Mounted 

Monitor 


Ckpt Mounted 
Regulator 


Output Filter 
(particle)? 


02 

Dilution 


CRU94 


CRU 120 


CRU 122 


EOS Feedback to pilot 


Sche'd Mx 


BIT 


Oxygen Sensor 
(type & where?) 


Pressure Sensor (type & where?) 


F-15E 


93% Efficient at .01 micron 


13X(2beds) 
OXY-SIV 5 


Packed 


Sieve bed outlet 


No Aircraft plenum; self 
replenishing 450 psig BOS 
(262 liter NTPD) 


94% @ 26.71pm, 90% @ 
351pm, 34% @ 100 Ipm 


Yes 


Yes (CRU-98) 


99.99% 
efficient @ .1 
micron 


Yes 


Yes 


No 


No 


Automatic activation of BOS, 
Master Caution, Oxygen 
Warning Light, BOS pressure 
displayed on CRU-98. None 
for seat mounted EOS. 


Inlet filter 
element change 
400 hour phase 


Power-up BIT every start 
up 


Zirconia oxygen 
sensor in monitor 
concentrator 


Cabin pressure sensor for calculation 
of PP02 in concentrator based 
monitor, Outlet pressure sensor 
automatically switching to BOS 
between 14 and 22 psig outlet 
pressure. 


F-16 


93% Efficient at .01 micron 


13X(2beds) 
OXY-SIV 5 


Packed 


Sieve bed outlet 


(lea) 250cu/in plenum 
single seat; (lea) 250 
cu/in plenum & (1 ea) 100 
cu/in plenum two seat. 


93% @ 26.71pm, 34% @ 
100 Ipm 


No 


Yes (CRU-98) 


.4 to .6 micron 


Yes 


No 


Yes 


No 


REOS manually activated. 
Feedback in the form of 
safety pressure breathing 
and REOS pressure gauge 


Inlet filter 
element change 
at 400 hours 


EBITpart of preflight, 
MBIT every 400 hours 
with the filter change or 
during fault isolation 
resulting from an Oxy- 
Low indication 


Zirconia oxygen 
sensor in panel 
mounted monitor 


Cabin pressure sensor for calculation 
of PP02 in panel mounted monitor, 
Product pressure sensed by airframe 
pressure switch set at 5 psig 
generating oxygen warning, 
Concentrator inlet pressure 
moinitored by airframe pressure 
switch set at 10 psig generating an 
oxygen caution 


F 22 


YES (0.6 micron) 


13X (3 beds) 


Immobilized 


YES 


NO 


94%-95% MAX 


YES 


YES 


YES (0.6 
micron) 


NO 


YES 


NO 


YES 


NO 


NO 


YES 


Zirconia 


Pressure switch on OBOGS outlet 1 








































F-35 


Yes (0.4 micron absolute) 


13X(2beds) 


Immobilized 


Yes 


Volumetric Plenum 


94 Max 


Yes 


Yes 


Yes 


No 


NO 


NO 


NO 


YES 


NO 


YES 


Zirconia 


Pressure switch at inlet to regulator 1 
and the system will automatically go 1 
to BOS because of low pressure 1 








































F-15C 




LOX 


N/A 


NO 


NO 


100 Max 


N/A 


YES 


NO 


Yes 


Yes 


No 


No 


No 


Yes 


No 


No 


Pressure switch to sense low 1 
pressure (aircraft) 1 






































|f-16 




LOX 


N/A 


NO 


NO 


100 MAX 


N/A 


Yes 


NO 


Yes 


YES 


NO 


NO 


NO 


YES 


NO 


NO 


Pressure switch to sense low 1 
pressure (aircraft) 1 




93% Efficient at .01 micron 


5AMG 


Packed 


Sieve bed Outlet 


97 cu/in bottle 


15 psig Inlet Pressure, 
92% @ 8.0 Ipm, 65% @ 
13.11pm, 34% 2 35 Ipm 


No 


Yes- Chest 
Mounted CRU- 
103 


.4 to .6 micron 


No 


No 


No 


No 


No Indication of being 
activated, Possibly need to 
turn off OBOGS outlet flow 
when activated. 


Concentrator 1- 
Level Test 400 
and filter change 


Pneumatic BIT prior to 
flight System Check 
using TTU-520 


Zirconia oxygen 
sensor 


Cabin Pressure to calculate PP02 


F/A-18 












50 psig Inlet Pressure, 
93% @ 13.11pm, 50% @ 
701pm, 40% @ 100 Ipm, 






































80 psig Inlet Pressure, 
93% @ 13.11pm, 50% @ 
701pm, 40% @ 100 Ipm 


























A- 10 


93% Efficient at .01 micron 


13X(2beds) 
OXY-SIV 5 


Packed 


Sieve bed outlet 


(lea) 250 cu/in plenum 
single seat 


93% @ 26.71pm, 34% @ 
100 Ipm 


No 


Yes (CRU-98) 


.4 to .6 micron 


Yes 


No 


Yes 


No 


REOS manually activated. 
Feedback in the form of 
satfety pressure breathing 
and REOS pressure gauge 


Inlet filter 
element change 
at 400 hours 


EBITpart of preflight, 
MBIT every 400 hours 
with the filter change or 
during fault isolation 
resulting from an Oxy- 
Low indication 


Zirconia oxygen 
sensor in under the 
panel mounted 
monitor 


Cabin pressure sensor for calculation 
of PP02 in panel mounted monitor 


L 








































Yes (0.6 micron) 


13X (6 beds) 


Immobilized 


Yes 


No 


94% max 


No 


Yes 


Yes 


No 


No 


No 


No 


No, manually activated 


Filter change 


Yes 


N/A 


Yes, inline on aircraft 1 








































B-2 


Yes (0.6 micron) 


13X(3beds) 


Immobilized 


Yes 


Yes 


94% max 


Yes 


Yes 


Yes 


No 


No 


No 


No 


Yes 


Filter change 


Yes 


Zirconia, OMC 


Yes 1 


T-6 


93% Efficient at .01 micron 


13X (2 beds) 
OXY-SIV 5 


Packed 


Sieve bed outlet 


~300 cubic inch (notCLSS) 


90% MIN@ 13.7 LPM 


YES 


YES 


99.99% 
efficient @ .1 
micron 


NO 


CRU-60 


NO 


NO 


NO 


Inlet filter 
element change 
at 400 hours 


Power-up BIT every start 
up 


Zirconia oxygen 
sensor in monitor 
concentrator 


Aircraft low pressure switch for 
OBOGS product gas. Cabin pressure 
sensor for calculation of PP02 in 
concentrator based monitor. 


V-22 


93% Efficient at .01 micron 


(2 beds) OXY- 
SIV MDX 


Packed 


Sieve bed outlet 


Built in plenum ~250 cubic 
inch 


80% MIN requirement @ 
30 LPM(30K ceiling) 


YES 


Yes- Chest 
Mounted CRU- 
103 


30 micron 


NO 


NO 


NO 


NO 


NO 


Inlet filter 
element change 
at 420 hours 


Power-up BIT every start 
up 


Zirconia oxygen 
sensor in monitor 
concentrator 


Cabin pressure sensor for calculation 
of PP02 in concentrator based 
monitor. 



Table A-l. Comparison of Various OBOGS in USAF and USN Aircraft. 



85 



(This Page Intentionally Left Blank) 



86 



Appendix B: 



Molecular Characterization - Neurotoxicity Assessment, 
Analysis of Symptoms, and Characterization of Chemicals 

B.1 Introduction 

One of the two working hypotheses proposed for this Aircraft Oxygen Generation Study 
addresses the potential for F-22 flight safety being compromised by the presence of toxic levels 
of contaminants in the air delivered from the on-board oxygen generation system (OBOGS) to 
the pilot. The presence of high levels of certain classes of chemicals present in jet fuel, jet oil, 
hydraulic fluid or their pyrolysis products could be a contributing factor in central nervous 
system (or respiratory) symptoms experienced by pilots and ground crew personnel. This 
remainder of this Appendix presents a discussion and description of the: 

• Neurotoxicity assessment conducted, 

• Field measurements obtained, 

• Hazard analyses conducted, 

• Symptoms (air and ground crew) assessed, and 

• Analysis of possible chemical causes. 

B.2 Neurotoxicity Assessment 

An extensive, multi-step, multi-disciplinary effort was undertaken by personnel from the 
USAF, Boeing, Lockheed Martin, and others to identify chemicals that might possibly enter a 
pilot's breathing air on the F-22 and account for acute central nervous system (CNS) effects. 
The process, termed the Molecular Characterization Matrix (MCM), began with the generation 
of a list of chemicals known to be present in jet fuel, jet oil, and hydraulic fluids used on the 
F-22, together with selected chemicals believed to be associated with the pyrolysis or 
degeneration of these petroleum products. The focus was on chemicals, gases, or aerosols whose 
presence in life support system (LSS) air was considered plausible by virtue of normal operation 
of the jet engine, or from leaks in seals, valves, or other conduits. 

As of January 24, 2012, 759 chemicals associated with the F-22 had been assessed. 
Examples of chemical classes assessed in the MCM included: 

• Alkanes/Alkenes/Alkynes 

• Alcohols/ Aldehydes 

• Dienes/Esters/Ketones 

• Organic Sulfur/Phosphorus compounds 

• Total volatile organic compounds 



87 



• Other gases (e.g., carbon monoxide, carbon dioxide, nitrogen, argon) 

In addition to these classes, the presence of aromatic hydrocarbons (e.g., toluene, benzene), 
halogenated hydrocarbons (e.g., trichloroethylene, freons), and other gases (e.g., hydrogen 
cyanide) was assessed. 

A Neurotoxicity Assessment Team, consisting of toxicologists and occupational health 
professionals, narrowed this list of 759 chemicals to a list of 208 chemicals shown to exert acute 
adverse effects on the CNS in human or experimental animal studies. To date, 126 chemicals in 
this subset have been detected in ECS air samples from ground and flight tests of the F-22. As 
an additional step, the Neurotoxicity Assessment Team consulted multiple data sources to 
identify the lowest concentration of each chemical in air associated with adverse CNS effects in 
humans or animals. 

Data that identified the lowest airborne concentration associated with the onset of central 
nervous system effects within 30 minutes to several hours was used by the team to derive a "red 
level" concentration. In most cases, the effect associated with the red level was a mild effect, 
such as mild central nervous system depression or altered response to external stimuli. 

B.2.1 Consensus Development 

For each significant decision in the analysis of CNS effects, input was obtained from 
three organizations, Lockheed Martin, Boeing, and the United States Air Force (USAF). A 
summary of the input from each organization was put into a working spreadsheet and then 
disseminated to the Neurotoxicity Assessment Team. A consensus was determined for each 
chemical and was listed on the MCM spreadsheet. 

B.2.2 Screening Gate 1 

Screening Gate 1 determined whether the CNS effects are a primary concern. At this 
level, a response of "Yes" was given if there were any CNS effects reported in animal tests or in 
human observations. If CNS effects have not been reported or if CNS effects were not expected 
based on the type of chemical, a response of "No" was entered. For example, short chain 
aldehydes got a "No" response for Screening Gate 1 because they are primarily irritants and not 
neurotoxic. The most common reasons for assigning a "No" at Decision Gate 1 was because the 
chemical listed on the MCM is known to be primarily an irritant, or because they were not a 
specifically identified chemical. 

B.2.3 Screening Gate 2 

Screening Gate 2 was intended to determine whether the CNS effects were primarily 
acute effects. Screening Gate 2 analysis was performed for all chemicals that received a "Yes" 
response to Decision Gate 1 . A "No" response to Decision Gate 2 was given if the evidence for 
CNS effects was only due to chronic or long-term exposures. Chemicals were deferred if the 
Neurotoxicity team was told that they were not expected to be on the aircraft. Deferred status is 
intended to allow for further analysis if it was deemed necessary. 



88 



B.2.4 CNS Effects Analysis 



B.2AA Data Sources 

The data sources used to make the determination of concentration associated with CNS 
effects included exposure limits documentation, databases that provide secondary reviews of the 
literature, abstracting services, and internal resources. To the extent possible, information was 
obtained from detailed descriptions so the type of effect and exposure concentration and duration 
could be identified. CNS effect levels were derived from exposure-effect data from exposures of 
30 minutes to several hours. 

The data sources consulted included, but were not limited to, authoritative exposure limit 
documentation such as: 

• American Conference of Governmental Industrial Hygienists (ACGIH) threshold 
limit values (TLV), 

• Spacecraft maximum allowable concentrations, 

• American Industrial Hygiene Association workplace environmental exposure limits, 

• Occupational safety and Health Administration (OSHA) permissible exposure levels 
(PEL), and 

• National Institute for Occupational Safety and Health recommended exposure limits 
and short term exposure limits. 

Also included were 

• Toxicological data contained in the National Institute of Occupational safety and 
Health Registry of Toxic Effects, 

• The National Library of Medicine Hazardous Substance Data Base, 

• The Canadian Center for Occupational Health and Safety database, 

• The National Library of Medicine TOXLINE database, and 

• Internal information resources of Boeing, Lockheed Martin, and the USAF. 

Data that identified the lowest airborne concentration associated with the onset of CNS 
effects within 30 minutes to several hours was used by the team to derive a "Red Level" 
concentration (see Section B.2.4. 3 below). In most cases, the effect associated with the red level 
was a mild effect, such as mild central nervous system depression or altered response to external 
stimuli. 

B.2A.2 Data Quality 

A wide range of data sources and data quality was used, in order to obtain data for as 
many chemicals as possible. Data sources ranged from full text or abstracts of published studies 
to brief descriptions from data compilations. Data from better descriptions were used in 
preference to data with limited descriptions or data from unverified sources. However, for many 
chemicals, the data on CNS effects were limited, and any available information was used. In 
some cases, data were limited to a brief report of CNS effects with limited information about the 



89 



effect observed or the experimental design. In the absence of better information, data of this type 
were used. However, most of the chemicals had data described adequately to determine with 
good confidence the level associated with CNS effects. 

B.2A.3 Concentration Associated with CNS Effects (Red Level) 

The concentration associated any CNS effects was determined for all chemicals that 
received a "Yes" response to Screening Gates 1 and 2 (see Sections B.2.2 and B.2.3 above). The 
concentration used for the red level was the lowest concentration found that was associated with 
any CNS effect, based on the available data and data summaries. Although data from better 
descriptions were preferred to data with limited descriptions, the lowest concentration reported to 
be associated with CNS effects may be based on a source with limited description. When limited 
information was available, it was assumed that any effect related to central nervous system 
function was a relevant CNS effect. Effects such as slight dizziness, CNS depression, vertigo, 
mild tremors, incoordination, or effects on any CNS function test, among many others, were 
used. 

No safety factors were routinely applied to the observed data in order to derive the red 
level. In cases with a well described concentration-response for CNS effects, the red level was 
selected to represent a lowest-observed adverse effects level. When more limited data was 
available, the concentration selected was intended to be the best estimate possible of the 
threshold for CNS effects. When there was doubt about the appropriate concentration, the lowest 
of the possible levels was used. The latter decision may introduce some safety margin due to 
limited information, but a safety factor for limited information, animal information, or based on 
exposure duration was not routinely applied. 

In cases with only animal data it is sometimes difficult to relate an observation to an 
equivalent human effect or to the equivalent exposure concentration or severity of effect. In 
these cases, animal effects were assumed to be relevant and to represent potential human effects 
on an equivalent basis. For example, an animal observation of mild CNS depression or altered 
response to external stimulus was assumed to relate directly to human CNS effects. In most 
cases, the effect associated with the red level was a mild effect. 

In cases with limited data, it is not possible to determine with certainty the type or 
severity of the effect associated with the reported concentration. In these cases, it was assumed 
that the reported effect and concentration from the data that was available were relevant to 
human CNS effects. It was also assumed that the concentration reported was the lowest 
concentration associated with CNS effects. These assumptions could not be verified in some 
cases. 

The ACGIH TLV documentation lists the primary effects that were the basis for setting 
the standard. When CNS effects were listed as one of the effects that were the basis of the 
exposure limit, the documentation was reviewed to determine whether CNS effects were the 
most sensitive effects that were the basis of the exposure limit. The TLV was used only when it 
was clearly associated with mild CNS effects. Otherwise the exposure concentration from 
studies reporting CNS effects was used. 



90 



B.2AA Yellow Level 



The yellow level was assigned by reducing the red level by a factor of 10-100. The 
yellow level is intended to be a de minimus concentration, and to indicate a concentration below 
which additional effort was not warranted. The yellow level is not associated with CNS effects, 
and exceeding the yellow level does not indicate a hazard. The yellow level indicates that the 
chemical may approach concentrations relevant to CNS effects (red level) due to the individual 
chemical or additive effects, so continued attention is appropriate. 

B.3 Field Measurements 

A series of field measurements were undertaken in ground and flight tests of F-22 aircraft 
to quantify concentrations of the narrowed list of MCM chemicals that were present in the 
environmental control system, with a particular focus on levels in air sampled at both the 
OBOGS inlet and outlet. Multiple engine sources and ECS configurations (using incident and 
non-incident engines and/or aircraft) and OBOGS were utilized for the data collection. The 
sampling media included sorbent tubes and air collected in summa canisters. Analytical 
methodology included Environmental Protection Agency (EPA) TO- 15 (utilizing gas 
chromatography/mass spectrometry to quantify 75 volatile organic compounds with known 
standards, and to tentatively identify and quantify other compounds by comparison with spectral 
libraries), EPA TO-15 (modified) to quantify C3-C12 hydrocarbons, EPA 25C to measure 
carbon monoxide (CO) and carbon dioxide (CO2), EPA 3C (modified) to quantify oxygen, 
nitrogen, and argon, and EPA TO- 11 to quantify aldehydes. Direct reading instruments were 
also utilized to measure certain contaminants, such as carbon monoxide, cyanide, and certain 
gases. The maximum value of each analyte identified during the course of the entire testing 
program was used to populate the MCM. 

During the course of the field measurement program, it was determined that initial tests 
conducted at Elmendorf Air Force Base (AFB) and Edwards AFB were subject to chemical 
artifacts arising from the use of isopropyl alcohol or Freon-based cleaning agents to clean the 
valves and tubing of the test collection equipment. Subsequent tests avoided the potential for 
such artifacts by using heated oxygen to clean and purge the test equipment. 

A few additional findings pertaining to the air measurements conducted on the F-22 merit 
brief discussion. A direct reading instrument, termed a ppbRAE, was used to measure total 
volatile organic compounds (VOCs) on the F-22 during ground and flight tests. Excluding 
transient peaks during engine start-up or shut-down, the maximum level of VOCs measured in 
ground and flight breathing air delivered to the pilots via the breathing regulator Breathing 
Regulator Anti-G (BRAG) valve was in the range of 1-5 parts per million (ppm). Steady state 
levels were typically below 1 ppm. These values, which are consistent with measurements 
routinely obtained aboard commercial aircraft 8 , are far below the values associated with acute 
CNS symptoms. The summa canister analyses on several F-22 tests detected the presence of 
tentatively identified and unidentified fluorocarbons, typically at an aggregate concentration of 
less than 1 milligram per cubic meter (mg/m 3 ). By way of comparison, it may be noted that 



Crump, D., et. al. "Aircraft Cabin Air Sampling Study (Parts 1 and 2)." 



91 



1-hour Spacecraft Maximum Allowable Concentration (SMAC) concentrations and TLVs for 
halogenated anesthetic gases are generally on the order of hundreds of mg/m 3 of air. The source 
of these fluorocarbons, which at the levels detected would not be expected to cause acute CNS 
depression, is undetermined. The possibility exists that the presence of fluorocarbons may be an 
artifact of the measurement collection equipment, in that they were detected in similar 
concentrations on air drawn through the test equipment prior to its installation on the F-22. Early 
direct measurement of post-BRAG valve air of an incident F-22 aircraft during a ground test in 
the spring of 2009 failed to detect any fluorocarbons. 

Table B-l and B-2 (below) identify specific VOCs detected in OBOGS inlet and outlet 
air. The maximum concentration measured in OBOGS outlet breathing air in either ground or 
flight tests at Elmendorf AFB and Edwards AFB (on days in which no cleaning agents were used 
to clean and purge the air collection equipment) is shown in Column 2. Column 3 depicts the 
corresponding red limit concentration for acute CNS effects associated with each chemical, and 
Column 4 indicates the hazard quotient (the maximum measured concentration divided by the 
red limit). 

The analysis of collected pre- and post-OBOGS air samples from ground and flight 
testing reveals no VOCs in breathing air at a concentration that represents and acute risk to 
health. To date, none of the chemicals detected in air supplied to the OBOGS or breathing air, 
including metabolic toxicants such as carbon monoxide, cyanide, or organophosphates, have 
been measured at concentrations associated with acute CNS symptoms or at levels that present 
an acute hazard to the pilot. Further, the analysis of the incident pilot clinical surveillance data 
to date reveals no alterations from baseline or normal values. 

BA Hazard Analysis 

Because the chemicals identified were all volatile organic compounds capable of exerting 
depressant effects on the CNS through a common mode of action, it is appropriate to calculate a 
hazard index which sums the hazard quotients (the maximum measured concentration divided by 
the red limit), according to the formula: 

Hazard Index = £ (Q / [red limit] i) 

where "C" is the maximum measured concentration of each chemical, and "red limit" is that 
chemical's respective red limit concentration. A hazard index less than 1.0 indicates that no 
acute adverse effects would be expected. A hazard index greater than 1.0 indicates that adverse 
effects are possible. 

Table B-l (below) shows the maximum concentrations for specific VOCs as measured at 
the OBOGS inlet during flight and ground testing. The Red Limit Concentrations for developing 
hazard quotients for each of the volatile organic compounds are also shown along with the 
associated hazard quotients. Note the overall Hazard Index, as derived from the summation of 
the individual Hazard Quotients is 0.21. 

Table B-2 (below) provides similar data for the corresponding flight and ground test data 
taken at the OBOGS outlet. The overall Hazard Index at the OBOGS outlet is 0.36, well below 
the value of 1.0 at which adverse effects are considered possible. This provides reassurance that 
the chemicals detected in OBOGS outlet breathing air sampled from the F-22 ground and flight 
test to date were unlikely to have accounted for CNS symptoms. 



92 



Note that the concentrations (OBOGS inlet/outlet) are in parts per billion by volume 
(ppbV). 



Chemical Name 


Times 
Detected 

(1 = at 
least once) 


Maximum 
Concentration 
at OBOGS Inlet 
(ppbV) 


Red Limit 

1 IU VI kll 1 II 1 

Concentration 
(ppbV) 


Hazard 
Quotient 


Argon 


20 


37,000,000 


330,000,000 


0.1121 


COo carbon dioxide 


29 


950 000 

w V-/ V-/ j V-/ V-/ V-/ 


20 000 000 


0.0475 


2-Prooanol (IsooroDvl 
Alcohol) (1-100) 


42 


8,200 


400,000 


0.0205 


Carbon Disulfide 


1 


20 


1,000 


0.02 


C8 as n-Octane 


6 


1,400 


1 ,000,000 


0.0014 


1,3-Dichloro- 
1,1,2,2,3- 
pentafluoropropane 
(HCFC-225cb) 


7 


1,205 


1 ,000,000 


0.0012 


Acetonitrile 


8 


45 


40,000 


0.0011 


alpha-Cumyl Alcohol 


7 


8.3 


10,000 


0.0008 


Toluene 


46 


40 


50,000 


0.0008 


2-Ethyl-1-hexanol 


7 


7.3 


10,000 


0.0007 


tert-Butanol 


1 


18.8 


50,000 


0.0003 


4-Methyl-2- 
pentanone 


3 


8.6 


25,000 


0.0003 


Ethyl Acetate 


30 


110 


400,000 


0.0003 


Acetone (0-1000) 


38 


150 


1 ,000,000 


0.0002 


1 ,2,4-Trimethyl 
benzene 


7 


11 


100,000 


0.0001 


m,p-Xylenes 


7 


9.7 


100,000 


<0.0001 


C12 as n-Dodecane 


9 


94 


1 ,000,000 


<0.0001 


C13H28 Branched 
Alkane 


7 


82 


1 ,000,000 


<0.0001 


Benzene 


9 


4.1 


50,000 


<0.0001 


C1 1 as n-Undecane 


12 


190 


2,400,000 


<0.0001 


C1 1 H24 Branched 
Alkane 


5 


72 


1 ,000,000 


<0.0001 


C10 as n-Decane 


11 


62 


1 ,000,000 


<0.0001 


C9 as n-Nonane 


7 


98 


1 ,600,000 


<0.0001 


Cyclohexane 


2 


15 


250,000 


<0.0001 


2,4-Dimethylheptane 


5 


52 


1 ,000,000 


<0.0001 


1,3,5- 
Trimethylbenzene 


6 


4.4 


100,000 


<0.0001 


o-Xylene 


6 


4.3 


100,000 


<0.0001 


4-Ethyltoluene 


6 


2.1 


50,000 


<0.0001 


2-Butanone (MEK) 


1 


7.8 


200,000 


<0.0001 


1,2,4- 
Trimethylbenzene 


1 


3.8 


100,000 


<0.0001 



93 



Methyl tert-Butyl 
Ether 


1 


1.8 


50,000 


<0.0001 


C4 as n-Butane 


10 


340 


10,000,000 


<0.0001 


C12H26 Branched 
Alkane 


18 


31 


1 ,000,000 


<0.0001 


4-Methyl octane 


9 


28.6 


1 ,000,000 


<0.0001 


Propene 


37 


1,500 


64,000,000 


<0.0001 


2-Methyl-1-pentene 


2 


20 


1 ,000,000 


<0.0001 


Naphthalene 


7 


1 


50,000 


<0.0001 


C6 as n-Hexane 


1 


2.8 


250,000 


<0.0001 


C7 as n-Heptane 


4 


11 


1 ,000,000 


<0.0001 


Ethylbenzene 


6 


1 


100,000 


<0.0001 


C10H22 Branched 
Alkane 


4 


8.6 


1 ,000,000 


<0.0001 


C15H32 Branched 
Alkane 


3 


7.1 


1 ,000,000 


<0.0001 


Methyldecalin Isomer 


1 


0.7 


100,000 


<0.0001 


C12H24 Compound 


1 


5.7 


1 ,000,000 


<0.0001 


2,4-Dimethyl-1- 
heptene 


1 


5 


1 ,000,000 


<0.0001 


C3 as Propane 


16 


1,400 


280,000,000 


<0.0001 


Styrene 


2 


0.2 


50,000 


<0.0001 


1 ,3-Butadiene 


6 


7.3 


2,000,000 


<0.0001 


n-Nonane 


1 


5.3 


1 ,600,000 


<0.0001 


Dodecane 


12 


6.5 


2,400,000 


<0.0001 


Cumene 


4 


0.5 


200,000 


<0.0001 


Undecane 


9 


5.5 


2,400,000 


<0.0001 


n-Octane 


1 


2 


1 ,000,000 


<0.0001 


C5 as n-Pentane 


6 


62 


32,000,000 


<0.0001 


2-Hexanone 


2 


1.6 


1 ,000,000 


<0.0001 


C11H22 Compound 


1 


1.3 


1 ,000,000 


<0.0001 


n-Heptane 


1 


0.8 


1 ,000,000 


<0.0001 


n-Propylbenzene 


5 


0.6 


2,000,000 


<0.0001 


Propylcyclohexane 


1 


1.7 


7,500,000 


<0.0001 


Isobutene 
Isobutylene 


5 


41 


198,000,000 


<0.0001 


Hazard Index 0.21 



Table B-l. Hazard Quotients and Hazard Index for Chemicals Measured at OBOGS 
Inlet. 



94 



Chemical name 


Times 

(1 = at least 
once) 


Maximum 
Concentration 

at OBOGS 
Outlet (ppbV) 


Red Limit 
Concentration 
(ppbV) 


Hazard 
Quotient 


Argon 


21 


46,000,000 


330,000,000 


0.1394 


C6 as n-Hexane 


1 


12,000 


250,000 


0.048 


Toluene 


70 


2,100 


50,000 


0.042 


2-Butanone (MEK) 


1 


7,800 


200,000 


0.039 


2-Propanol (Isopropyl 
Alcohol) (1-100) 


59 


1 1 ,000 


400,000 


0.0275 


C0 2 carbon dioxide 


18 


510,000 


20,000,000 


0.0255 


n-Hexane 


1 


3,700 


250,000 


0.0148 


C7 as n-Heptane 


1 


1 1 ,000 


1 ,000,000 


0.011 


C8 as n-Octane 


16 


3,000 


1 ,000,000 


0.003 


Cyclohexane 


1 


640 


250,000 


0.0026 


2-Ethyl-1-hexanol 


11 


16 


10,000 


0.0016 


alpha-Cumyl Alcohol 


7 


11 


10,000 


0.0011 


Acetone (0-1 000) 


42 


650 


1 ,000,000 


0.0007 


Methyldecalin Isomer 


1 


43 


100,000 


0.0004 


tert-Butanol 


1 


20 


50,000 


0.0004 


1,3-Dichloro-1, 1,2,2,3- 
pentafluoropropane 
(HCFC-225cb) 


16 


350 


1 ,000,000 


0.0003 


m,p-Xylenes 


19 


26 


100,000 


0.0003 


1 ,2,4-Trimethyl 
benzene 


7 


4 


100,000 


<0.0001 


C12 as n-Dodecane 


8 


94 


1 ,000,000 


<0.0001 


Ethanol (50-1000) 


1 


87 


1 ,000,000 


<0.0001 


C10 as n-Decane 


13 


83 


1 ,000,000 


<0.0001 


Ethyl Acetate 


40 


33 


400,000 


<0.0001 


Benzene 


7 


4 


50,000 


<0.0001 


4-Methyl-2-pentanone 


2 


2 


25,000 


<0.0001 


n-Heptane 


1 


80 


1 ,000,000 


<0.0001 


C1 1 as n-Undecane 


11 


190 


2,400,000 


<0.0001 


C13H28 Branched 
Alkane 


5 


78 


1 ,000,000 


<0.0001 


C9 as n-Nonane 


7 


98 


1 ,600,000 


<0.0001 


C12H26 Branched 
Alkane 


17 


58 


1 ,000,000 


<0.0001 


2,4-Dimethylheptane 


8 


46 


1 ,000,000 


<0.0001 


Acetonitrile 


4 


2 


40,000 


<0.0001 


1,3,5- 
Trimethylbenzene 


10 


4 


100,000 


<0.0001 


4-Methyl octane 


11 


42 


1 ,000,000 


<0.0001 


1,2,4- 
Trimethylbenzene 


1 


4 


100,000 


<0.0001 


C12H24 Compound 


1 


37 


1 ,000,000 


<0.0001 



95 



o-Xylene 


9 


3 


100,000 


<0.0001 


Propene 


43 


1,800 


64,000,000 


<0.0001 


Naphthalene 


2 


1 


50,000 


<0.0001 


2-Methyl-1-pentene 


1 


22 


1 ,000,000 


<0.0001 


Ethylbenzene 


8 


2 


100,000 


<0.0001 


C11H24 Branched 
Alkane 


7 


18 


1 ,000,000 


<0.0001 


n-Nonane 


1 


17 


1 ,600,000 


<0.0001 


Styrene 


1 


1 


50,000 


<0.0001 


C5 as n-Pentane 


4 


330 


32,000,000 


<0.0001 


Tetrahydrofuran (THF) 


1 


2 


190,000 


<0.0001 


C15H32 Branched 
Alkane 


6 


9 


1 ,000,000 


<0.0001 


n-Octane 


1 


4 


1 ,000,000 


<0.0001 


C4 as n-Butane 


8 


35 


10,000,000 


<0.0001 


4-Ethyltoluene 


1 


0.2 


50,000 


<0.0001 


Dodecane 


13 


4 


2,400,000 


<0.0001 


2-Hexanone 


1 


1.4 


1 ,000,000 


<0.0001 


C3 as Propane 


13 


340 


280,000,000 


<0.0001 


1 ,3-Butadiene 


1 


1.3 


2,000,000 


<0.0001 


Undecane 


12 


1.3 


2,400,000 


<0.0001 


Isobutene Isobutylene 


2 


40 


198,000,000 


<0.0001 


n-Propylbenzene 


1 


0.15 


2,000,000 


<0.0001 


Hazard Index 0.36 



Table B-2. Hazard Quotients and Hazard Index for Chemicals Measured at OBOGS 
Outlet. 

B.5 Symptom Analysis and Possible Causes 

Recent ground and flight testing of the F-22 LSS has demonstrated that numerous volatile 
organic chemicals that are constituents of ambient air, polyalphaolefin, and Petroleum, Oils and 
Lubricants, and are consistently present at the inlet and outlet of the OBOGS. Such 
contamination of the breathing air is assumed to be typical of LSS utilizing engine bleed air. The 
presence of such contaminants is also well documented in the commercial airline industry. The 
LSS of the F-22 was not designed to filter volatile contaminants from bleed air; however, recent 
testing indicates OBOGS can reduce the concentration of some chemicals in the product gas 
while concentrating others such as argon. The contaminants measured were found at low levels 
and were determined to be below the concentrations associated with health risks in humans. 

B.5.1 CNS Symptoms 

Notwithstanding the levels of contaminants measured, the Study Panel heard evidence 
that F-22 pilots and ground personnel reported CNS symptoms consistent with hypoxia or 
exposure to a toxic substance. A molecular characterization effort that is ongoing has been 
designed to identify all potential airborne toxicants in the F-22, determine the ability of these 
chemicals to enter the breathing air, and the ability of these chemicals, either individually or in 



96 



aggregate, to cause acute CNS toxicity in humans. The potential for a toxicant entering the 
breathing air at a hazardous concentration is not ruled out as a cause of pilot symptoms; however 
evidence for this possibility was not found in ground and flight testing to date. 

The neurons of the central nervous system have little capacity for anaerobic metabolism 
and thus are exquisitely sensitive to inadequate oxygen (hypoxia) or a lack of oxygen (anoxia). 
The term anoxic anoxia refers to a primary lack of blood oxygen in the presence of an otherwise 
adequate blood supply to the tissues. This condition can be caused by a lack of oxygen in the 
breathing air, respiratory failure or a decreased oxygen delivery capacity of the blood as in the 
case of CO poisoning. Ischemic anoxia is caused by decreased arterial pressure, decreased 
cardiac output, or by vascular occlusion. Cytotoxic anoxia results from an inhibition of cellular 
metabolism at the tissue and cellular level in the presence of adequate supply of both blood and 
oxygen. This later condition can result from exposure to toxic levels of metabolic inhibitors such 
as cyanide. In toxicology, anoxia can be a prototype for CNS injury as many neurotoxicants 
mimic anoxia to some degree. The symptoms of hypoxia can also be confused with the signs of 
acute solvent intoxication as discussed below. 

There are a large number of VOCs that can depress CNS function causing what are 
known as "acute solvent effects." A list of over 500 chemicals that can cause acute CNS Solvent 
Syndrome and their toxicological information has been published on TOXNET. Solvents 
(including gas anesthetics) enter the CNS primarily through the respiratory track and, due to their 
high lipid solubility, rapidly enter the blood stream, and then pass through the blood brain barrier 
into the CNS. Their effect is primarily to slow the propagations of action potentials along nerve 
cells and thus depress CNS function. Symptoms of acute CNS Solvent Syndrome caused by 
exposure to toxic levels of these chemicals can cause signs such as difficulty concentrating, 
confusion, dizziness, fatigue, headache, inebriation, irritability, impaired speech, lethargy, 
stupor, coma, and death. Many of these toxic effects can be reversed by removing the individual 
from the toxic environment into fresh air. It is this group of compounds, VOCs, which are the 
major constituents of jet fuels, engine oils, lubricating fluids, and hydraulic fluids. Like with any 
substance, the dose of the substance to which an individual is exposed, the route of exposure, and 
the sensitivity of the individual determines if the exposure will cause toxicity. The majority of 
VOCs have threshold values below which no clinical signs of toxicity are expected to occur. For 
many VOCs encountered in the work place, occupational exposure levels have been established 
that are designed to provide significant margins of safety for individuals who are exposed in their 
daily activities. In fact, VOCs at some level are present in atmospheric air samples and are 
significant constituents of air pollution and smog. 

In most of the recent cases of hypoxia or hypoxia like incidents reported during F-22 
operations, the signs and symptoms of the affected pilots were determined to be consistent with 
hypoxia caused by delivery of inadequate levels of oxygen in the breathing air. However, the 
causes of a number of breathing air anomalies remain unknown. When hypoxia develops 
gradually, the symptoms may include difficulty concentrating, headache, fatigue, shortness of 
breath, a feeling of euphoria and nausea. In hypoxia of very rapid onset, changes in vision, 
levels of consciousness, seizures, coma, and death occur. Pilots train to quickly recognize this 
condition and to respond with deployment of emergency oxygen systems. The symptoms 
typically disappear promptly upon receipt of adequate oxygen. Hypoxia caused by exposure to 
toxic levels of certain metabolic poisons such as CO and cyanide, on the other hand, prevent the 
delivery of oxygen to the tissues and the resultant CNS effects of acute high dose exposure are 



97 



not rapidly reversible. Furthermore, exposure to these two compounds results in formation of 
specific biomarkers of toxicity that can be readily measured in clinical samples. No clinical 
samples collected to date from incident personnel have shown such abnormalities. 

B.5.2 Respiratory Symptoms 

The Study Panel heard anecdotal reports that F-22 pilots frequently experience 
respiratory complaints within minutes to hours after completion of a sortie. The complaints were 
dominated by the occurrence of a mild to moderate non-productive cough unaccompanied by 
fever or other systemic symptoms. The Study Panel heard preliminary results of a formal survey 
of the F-22 and F-16 pilot community in which 65% of F-22 pilot respondents reported the 
occurrence of a cough during or shortly after some sorties, compared to 16% of F-16 pilot 
respondents. In addition, a significant number of F-22 pilots reported symptoms consistent with 
chest tightness. The temporal pattern of these respiratory symptoms does not appear to be 
consistent with acceleration atelectasis, a well-described entity in aviation medicine that is 
typically associated with the rapid onset of short-lived cough, chest tightness, or dyspnea. 
Consequently, a formal clinical and epidemiological investigation of the respiratory complaints 
is recommended. Irritant effects of ozone, volatile organic compounds, and inorganic gases and 
fine particulates have been associated with dry cough and chest tightness. Immunological 
responses, including antigen induced asthma or hypersensitivity pneumonitis, may also be 
associated with symptoms of this nature. 

B.6 Possible Causes 

The following sections address selected chemicals (VOCs and others) that the Study 
Panel found to be of primary interest as possible causes of various respiratory and CNS-type 
symptoms experienced by F-22 Raptor air and ground crew. 

B.6.1 Carbon Monoxide 

Carbon Monoxide has a well-characterized dose-dependent capacity to cause decrements 
in central nervous system function that may be accompanied by symptoms of lightheadedness, 
dizziness, diminished capacity to concentrate, and headache. Accordingly, the potential role of 
carbon monoxide as a cause of hypoxia- like incidents has been carefully considered by the AOG 
Study Panel. Carbon monoxide exposure to F-22 aircrew has been assessed by two independent 
approaches: (1) real-time measurement of carbon monoxide using multi-RAE or Gray wolf TG- 
501 direct reading instruments on the flight-line, or in the cockpit or OBOGS outlet during 
ground or flight operations, and (2) post-exposure measurement of carboxyhemoglobin in the 
blood of personnel. The flight-line measurements found CO values to average less than 15 ppm, 
with transient excursions to 15 to 50 ppm in the immediate vicinity of engine exhaust. Cockpit 
and OBOGS outlet measurements during ground and flight operations averaged less than 2 ppm, 
with transient spikes in the cockpit of up to 8.5 ppm during transition points of ground operation 
including auxiliary power unit (APU) on/off, engine on/off, or canopy open/close. 
Carboxyhemoglobin measurements of aircrew were almost always less than 3 percent, with one 
confirmed value of 4 percent. 

Extensive human studies have examined the relationship between carbon monoxide 
exposure and carboxyhemoglobin levels, and in turn, the impact of carboxyhemoglobin levels on 
central nervous symptoms and human performance. The EPA published an extensive assessment 



98 



of the health effects of low-level carbon monoxide exposure. 9 With respect to the impact of 
carbon monoxide on human behavior and neurological performance, the EPA concluded: 

In summary, no reliable evidence demonstrating decrements in neural or 
behavioral function in healthy young adult humans has been reported for 
carboxyhemoglobin levels below 20%, and even those studies are untested by 
replication. The low carboxyhemoglobin behavioral effects that have sometimes 
been reported cannot be taken at face value because they are not reliably 
repeatable, and they do not fit into wider range, dose-effect patterns reported in 
other studies. It is more reasonable to conclude that no statistically detectable 
behavioral impairments occur until carboxyhemoglobin exceeds 20 to 30%. 
Significant behavioral impairments in healthy individuals should not be expected 
until carboxyhemoglobin levels exceed 20%. 10 

In like manner, a meta-analysis 11 analyzed data from multiple controlled animal 
experiments, as well as published human data on hypoxic hypoxia, based on the premise that the 
neurotoxicity of carbon monoxide is largely attributable to diminished oxygen delivery to the 
brain. This analysis concluded that "for healthy sedentary persons, 18-25%) carboxyhemoglobin 
would be required to produce a 10% decrement in behavior," (i.e., 10% change in 
neurobehavioral test performance). A 10% decline from average values would represent a 
relatively small effect that would still be well within the normal spectrum of human 
performance. 

Controlled human study of the relationship between carbon monoxide inhalation and 
carboxyhemoglobin levels have yielded models, such as the Coburn, Forster, and Kane (CPK) 
equation that have been validated during rest and exercise. The CPK equation predicts that the 
level of carbon monoxide exposure resulting in a carboxyhemoglobin value of 20% would 
include 1,000 ppm for approximately 40 minutes, 500 ppm for approximately 90 minutes, or 200 
ppm for approximately 400 minutes. 12 These values exceed the pattern of carbon monoxide 
exposure documented during all phases of F-22 operation by at least two orders of magnitude. 
Based on all of the foregoing, it may be concluded that CO exposure to F-22 pilots or ground 
crew is far below that capable of causing the overt central nervous system symptoms that have 
been the subject of current investigation. 



United States Environmental Protection Agency. "Air Quality Criteria for Carbon Monoxide 
(EPA600/P-99/001F)." 

10 Ibid. 

11 Benignus, V. "Behavioral Effects of Carbon Monoxide: Meta Analyses and Extrapolation." 

12 Peterson, J., & Stewart, R. "Predicting the Carboxyhemoglobin Levels Resulting from 
Carbon Monoxide Exposures." 



99 



B.6.2 Carbon Dioxide 



Carbon dioxide is present in the atmosphere from natural and anthropogenic sources (e.g. 
the combustion of fossil fuels). The global average marine surface atmospheric concentration 
was estimated to be 389 ppm (slightly less than 0.04%) in 2010. Health effects potentially 
associated with CO2 inhalation by servicemen in military settings have been evaluated in two 
major reviews. 14 ' 15 As described in both documents, sufficiently elevated concentrations of 
carbon dioxide can result in acute CNS and constitutional symptoms, including decrements in 
visual and auditory acuity, impaired cognition, headache, and shortness of breath. By activating 
central and peripheral chemoreceptors, carbon dioxide concentrations as low as 1.0% elicit a 
hyperventilatory response. That response is not a toxic effect per se, and at low levels 
acclimatization occurs. A National Research Council (NRC) report on Spacecraft Maximum 
Allowable Concentrations 16 concluded that mild CNS depression can occur after acute exposure 
to atmospheres containing 5% CO2. The no-observed adverse effect level for acute exposure 
(hours to days) was 4%; that for sub-chronic exposures (days to weeks) was 3%. After 
application of a safety margin adjusting for the small number of subjects in the key studies, the 1 
hour and 24 hour SMAC was set at 1.3% CO2 (i.e. 13,000 ppm), with CNS depression and 
visual disturbance as the target toxicity. The 2007 NRC report 17 took note of two small studies 
(each n = 3) that found a subclinical impact on visual tracking and depth perception after acute (1 
hour) exposure to 2.5% CO2, and designated this as an acute lowest observed adverse effect 
level. Because the effect was subtle, reversible, and of questionable toxicologic and operational 
significance, no safety margin was applied, and the 1 hour and 24 hour Emergency Exposure 
Guidance Level was set at 2.5% CO2 (25,000 ppm). The OSHA permissible exposure limit for 
CO2 as an 8-hour time weighted average is 5,000 ppm, which OSHA sought unsuccessfully to 
raise to 10,000 ppm in 1989. 

Carbon dioxide concentrations in the F-22 have been measured using two different 
methods. Summa canisters were used to sample for CO2 at the OBOGS inlet and outlet in flight 
tests with numerous configurations in the summer of 2011. Paired measurements typically 
demonstrated a significant decline in CO2 measured at the outlet compared to the inlet. The 
maximum (unpaired) inlet and outlet CO2 concentrations were 950 ppm and 510 ppm, 
respectively. Outlet CO2 concentrations less than 100 ppm were frequently observed. In the fall 



13 Biasing, T. "Recent Greenhouse Gas Concentrations." 

14 National Research Council (Committee on Toxicology). "Carbon Dioxide. In Emergency and 
Continuous Exposure Guidance Levels for Submarine Contaminants." 

15 Wong, K. "Carbon Dioxide. In Subcommittee on Spacecraft Maximum Allowable 
Concentrations National Research Council, Spacecraft Maximum Allowable Concentrations 
for Selected Airborne Contaminants (Volume 2)." 

16 Ibid. 

17 National Research Council (Committee on Toxicology). "Carbon Dioxide. In Emergency and 
Continuous Exposure Guidance Levels for Submarine Contaminants." 



100 



of 201 1, the Technical Assistance ("107") Team used a real-time instrument to obtain continuous 
measurements of CO2 in the cockpit of incident F-22 aircraft during ground tests. Spikes in CO2 
up to 2,500 ppm were observed for a few minutes during transitional events such as such as APU 
start/stop, engine on/off/military power, canopy open/close, followed by rapid declines to 100 to 
1,500 ppm with continued engine operation. It may be seen that the CO2 measurements obtained 
in F-22 have been one to two orders of magnitude lower than those associated with even 
subclinical CNS effects. Based on these results, CO2 exposure from an external source is not 
suspected of having contributed to acute CNS effects among F-22 air crew members. 

B.6.3 Ozone 

Ozone merits consideration as a potential contributor to respiratory complaints 
experienced by F-22 pilots. At sufficiently high doses, ozone exposure has been associated with 
respiratory complaints that commonly include cough, chest tightness, and discomfort on deep 
inspiration. 18 Exposure to atmospheric ozone increases at higher altitudes (e.g., at or above 
32,000 feet), and at high latitudes (e.g., toward the polar regions). In this regard, it is notable 
that preliminary findings of a survey of F-22 pilots found increased respiratory complaints after 
high altitude sorties. Short-term tolerance to the respiratory effects of ozone develops with 
consecutive daily exposure. 19 This might contribute to a variable association between ozone 
exposure and respiratory complaints among pilots whose flight schedules and flight profiles vary 
across a week. 

Without catalysts that eliminate ozone, cabin ozone concentrations in commercial aircraft 
not uncommonly reach levels ranging from those associated with subclinical pulmonary 
inflammation in susceptible individuals (0.06 ppm) to overt symptoms in many individuals (at or 
above 0.25 ppm). 18 ' 20 Levels of ozone as high as 1.0 ppm have been recorded in the cabin air of 
some aircraft. 21 Federal Aviation Administration aircraft air quality operating standards for 
ozone are at or below 0.25 ppm (ceiling) when operating above 32,000 feet, and at or below 0.1 
ppm Time Weighted Average during any 4-hour interval above 27,000 feet. Compliance with 
these standards on commercial aircraft requires use of a catalyst. Such devices are not present on 
the F-22. The extent to which the F-22's jet engine compressors would reduce the ozone 
concentration in bleed air below atmospheric levels, and the extent to which avionics might 
produce ozone, have not been investigated. 

In what was termed a "limited screen of cockpit air," passive samplers were utilized to 
measure in-flight levels of ozone during 12 F-22 sorties at Langley AFB in the late winter of 



McDonnell, W., et. al. "Ozone-Induced Respiratory Symptoms: Exposure-Response Models 
and Association with Lung Function." 

19 Gong, H., et. al. "Attenuated Response to Repeated Daily Ozone Exposures in Asthmatic 

Subjects." 

20 Kim, C, et. al. "Lung Function and Inflammatory Responses in Healthy Young Adults 
Exposed to 0.06 ppm Ozone for 6.6 Hours." 

21 Spengler, J., et. al. "Ozone Exposures During Trans-Continental and Trans-Pacific Flights." 



101 



2011. 11 The average of 12 samples was 0.016 ppm; the range was not reported. The altitude and 
latitude associated with these sorties was not provided. Interestingly, passive ozone sampling on 
the flight line yielded an average ozone concentration of 0.14 ppm. 

A laboratory investigation undertaken by the USAF School of Aerospace Medicine found 
that an OBOGS operated at a simulated aircraft altitude of 40,000 feet and a cabin altitude of 
8,000 feet diminished ozone levels between inlet gas and product gas by three orders of 
magnitude. 23 It was predicted that at a worse case inlet concentration of 16 ppm ozone, the 
outlet air would contain 0.038 ppm ozone, a level associated with olfactory awareness but devoid 
of adverse respiratory effects. It was recommended that valves and other components of an 
OBOGS be constructed of materials resistant to the corrosive oxidizing effect of high ozone 
concentrations. Based on all of the foregoing, ongoing investigations of respiratory complaints 
experienced by F-22 pilots should examine the potential contributory role of ozone, and should 
consider more extensive characterization of aircrew ozone exposure. 

B.6.4 Argon 

Like other oxygen concentration systems utilizing synthetic zeolites, the F-22 OBOGS 
concentrates argon, an inert gas that naturally occurs in the atmosphere at a concentration of 
0.94% by volume. As with oxygen, the degree of concentration is approximately 4- to 5-fold, 
and as expected, the maximum argon concentration detected in F-22 OBOGS outlet (product) 
gas was 4.6 percent. Adverse health effects associated with long-term inhalation of air with this 
concentration of argon have not been reported. The Department of Energy (DoE) TEEL-0 value 
(Temporary Emergency Exposure Limit) for argon, defined as a "threshold concentration below 
which most people will experience no appreciable risk of health effects" is 60,000 ppm, or 6 
percent. 24 Argon has a density greater than oxygen, but at the concentrations of less than 7 
percent customarily found in oxygen concentrators, it does not alter the flow characteristics of air 
or appreciably increase the work of breathing. 25 ' 26 

At normobaric pressure, argon acts as a simple asphyxiant gas. It becomes hazardous 
only at concentrations that are high enough to displace a significant proportion of oxygen in the 
inhaled atmosphere. The DoE TEEL-2 value for argon, defined as "the maximum airborne 
concentration below which it is believed that nearly all individuals could be exposed without 
experiencing or developing irreversible or other serious health effects or symptoms which could 



United States Air Force School of Aerospace Medicine. "Consultative Letter: Initial Screening 
of F-22 Raptor Fleet for Environmental Contaminants that May cause "Hypoxia-Like" 
Symptoms." 

Miller, G. "Ozone Contaminant Testing of a Molecular Sieve Oxygen Concentrator (MSOC)." 

United States Department of Energy. "Temporary Emergency Exposure Limits for 
Chemicals: Methods and Practice (DOE-HDBK-1046)." 

Friesen, R. "Oxygen Concentrators and the Practice of Anaesthesia." 

Shulagin, Y., et. al. "Effects of Argon on Oxygen Consumption in Humans During Physical 
Exercise Under Hypoxic Conditions." 



102 



impair an individual's ability to take protective action" is 230,000 ppm, or 23 percent. If 
normobaric gas mixtures are formulated to provide an adequate concentration of oxygen, much 
higher concentrations of argon can be tolerated without adverse effects. In an experimental 
protocol, no CNS effects were experienced by 4 Navy divers breathing a normobaric mixture of 
69 percent argon, 1 1 percent nitrogen, and 20 percent oxygen for 2 minutes. 28 Ten subjects had 
no decrement in computational ability or subjective rating of narcosis after breathing a 

29 

normobaric mixture of 80% argon and 20% oxygen for 2 to 8 minutes. In a study of staged 
decompression simulating extravehicular space activity by astronauts, 40 volunteers were 
administered either 100% oxygen or a mixture of 62% argon and 38% oxygen (ARGOX) for 4 
hours prior to full decompression to a 3.5 psia atmosphere. 30 The ARGOX mixture was 
associated with an increased occurrence of symptoms of decompression sickness, but acute 
central nervous deficits were not reported. 

When delivered at elevated atmospheric pressure, air mixtures enriched in argon have 
depressant effects on the central nervous system. In the study 28 cited above, effects of argon on 
the cognition of divers were apparent at 4 atmospheres (atm) pressure; a similar narcosis-like 
effect was evident in animals exposed to argon at 4 atm. 31 Argon at approximately 15 to 20 atm 
pressure produces frank anesthesia, ' an effect possibly mediated by agonist effects on respond 
to the gamma-aminobutyric acid (GAB A) receptors in the brain. Recent studies have suggested 
a metabolic effect of high concentrations of argon delivered at normobaric pressure. Human 
volunteers inhaling atmospheres containing either 85% argon and 15% oxygen, or 30% argon 
and 15%) oxygen and 55% nitrogen, exhibited a slight increase in oxygen consumption during 
exercise, without a decrement in capillary hemoglobin oxygen saturation compared to exercise 
on 85%o nitrogen and 15% oxygen. 34 This was interpreted as a protective ability of argon to 
enhance the efficiency of oxygen utilization by tissues during hypoxic stress. Recently, a 
neuro-protective role of 50%) argon and 50%) oxygen following cerebral ischemia was 



United States Department of Energy. "Temporary Emergency Exposure Limits for 
Chemicals: Methods and Practice (DOE-HDBK-1046)." 

Behnke, A., & Yarbrough, O. "Respiratory Resistance, Oil-Water Solubility, and Mental 
Effects of Argon, Compared with Helium and Nitrogen." 

Fowler, B., & Ackles, K. "Narcotic Effects in Man of Breathing 80-20 Argon-Oxygen and Air 
under Hyperbaric Conditions." 

Pilmanis, A., et. al. "Staged Decompression to 3.5 PSI Using Argon-Oxygen and 100% 
Oxygen Breathing Mixtures." 

Bennett, P. "Prevention in Rats of Narcosis Produced by Inert Gases at High Pressures." 

Friesen, R. (1992). "Oxygen Concentrators and the Practice of Anaesthesia." 

Abraini, J., et. al. "Gamma-aminobutyric Acid Neuropharmacological Investigations on 
Narcosis Produced by Nitrogen, Argon, or Nitrous Oxide." 

Shulagin, Y., et. al. "Effects of Argon on Oxygen Consumption in Humans During Physical 
Exercise Under Hypoxic Conditions." 



703 



demonstrated in an animal model of stroke. These observations, which utilized high 
concentrations of argon delivered at normal or elevated pressure, appear to have limited, if any, 
implications regarding the health impact of breathing air on the F-22, which is not known to 
exceed 5 percent argon at normobaric pressure. 

B.6.5 Tricresyl Phosphates 

Recent reports have suggested the possibility that tricresyl phosphates (TCPs) and related 
organophosphate compounds, sometimes used as additives (1-5% by weight) in aircraft hydraulic 
fluids and engine oils, may contaminate engine bleed air as a consequence of worn or faulty 
seals, and contribute to adverse health effects among pilots and flight crews. 36 ' 37 Certain TCPs 
have been associated with peripheral neuropathy following high exposure in experimental 
animals and humans. 38 ' 39 ' 40 The capacity of TCPs to promptly induce central nervous system 
depression or related symptomatology following acute inhalation as a fine mist or aerosol has not 
been established. In addition, there is no indication that human inhalation of TCP at a dose 
capable of causing overt acute CNS manifestations could occur in the absence of subsequent 
peripheral neuropathy. 

Recent studies have detected measurable quantities of TCPs in the cabin air of 
commercial 41 and military aircraft, 42 apparently as a result of contamination of engine bleed air. 
In the study conducted by investigators at Cranfield University in the United Kingdom, TCPs 
were detected in 25 of 100 test flights of commercial aircraft. 43 The maximum concentration 
was 37.7 micrograms per cubic meter (|ug/m ) (22.8 |ug/m triorthocresyl phosphate (TOCP) plus 
14.9 |ug/m 3 other TCP isomers), which occurred as a short term (5 minute) peak value during a 
climb at high throttle. This observation was an outlier — the 95 th percentile for the total TCPs for 
the climb phases of all flights was 0.2 |ug/m 3 . No acute central nervous system symptoms were 
reported by flight crews who sustained these exposures, which were well below regulatory 



Ryang, Y., et. al. "Neuroprotective Effects of Argon in an In Vivo Model of Transient Middle 
Cerebral Artery Occlusion in Rats." 

36 Crump, D., et.al. "Aircraft Cabin Air Sampling Study (Parts 1 and 2)." 

37 Harrison, R., et. al. "Exposure to Aircraft Bleed Air Contaminants Among Airline Workers: A 
Guide for Health Care Providers." 

38 Siegel, J., et. al. "Effects on Experimental Animals of Long-Term Continuous Inhalation of a 
Triaryl Phosphate Hydraulic Fluid." 

39 Freudenthal, R., et. al. "Subchronic Neurotoxicity of Oil Formulations Containing Either 
Tricresyl Phosphate or Tri-Orthocresyl Phosphate." 

40 Craig, P., & Barth, M. "Evaluation of the Hazards of Industrial Exposure to Tricresyl 
Phosphate: A Review and Interpretation of the Literature." 

41 Crump, D., et.al. "Aircraft Cabin Air Sampling Study (Parts 1 and 2)." 

42 DeNola, G., et. al. "Determination of Tricresyl Phosphate Air Contamination in Aircraft." 

43 Crump, D., et.al. "Aircraft Cabin Air Sampling Study (Parts 1 and 2)." 



104 



limits. In particular, the TOCP concentration did not exceed the OSHA PEL for TOCP of 100 
|ug/m 3 as an 8 hour time weighted average, or the United Kingdom short term exposure limit of 
300 |ug/m 3 over 15 minutes. 44 There was no apparent correlation between TCPs and total VOCs, 
which typically ranged between 0.5 to 2 ppm during flight segments. A recent study reported on 
TCP concentration in 78 air samples obtained on military aircraft with a history of engine bleed 
air contamination. 45 The airborne concentrations of TCP in the cockpit/flight revealed generally 
low concentrations of TCP (less than 5 |ug/m 3 ) with the exception of two results (51.3 and 21.7 1 
|ug/m 3 ), the highest of which was associated with an engine oil spill and overt smoke in the 
cockpit. Full-throttle ground testing of the cabin air of a propeller model aircraft during an 
active turbine oil leak associated with the odor of burned oil yielded a median TCP concentration 
of 5.5 |ug/m 3 (range 3.6 - 5.9 |ug/m 3 ), with no ortho-isomers detected. 46 

Sampling for TCPs in the F-22 was conducted in ground tests of cockpit air in incident 
aircraft in the fall of 2011 (40 samples), and with swabs from engine surfaces in contact with 
bleed air in incident and non-incident engines at Elmendorf AFB in the late spring of 2011 (12 
samples), and in incident jets in the fall of 201 1 (20 samples). No TCPs were detected in any of 
these samples. The limit of detection for the air samples (based on determinations utilizing 
mixed cellulose ester filter cassettes on F-22 jet #42) was approximately 8 |ug/m 3 for TOCP and 
40 |ug/m 3 for other isomers of TCP. These negative findings, combined with the known features 
of TCP intoxication, indicate that aircrews were unlikely to have sustained exposure to TCP of 
sufficient magnitude to result in sudden acute CNS symptoms. The low concentrations of other 
hydrocarbons associated with hydraulic fluid or engine oil measured in the engine bleed air of 
the F-22 offers additional reassurance that any TCPs possibly present were likely to have existed 
at comparably low levels. A biomarker of human TOCP exposure, based on detection of 
phosphorylated butylcholinesterase in serum, is currently under development. 47 Its availability 
in the future might enable bio-monitoring for TOCP to supplement industrial hygiene 
measurements. 

B.7 Summary 

In summary, based on analysis of available data, the AOG Study Panel concludes that 
trace levels of VOCs and other chemicals are commonly present in the breathing air supplied by 
the OBOGS used in the F-22. The origin of these contaminants in the breathing air can be traced 
to their presence in atmospheric air and to leaks of small quantities of jet fuel, oil, or hydraulic 
fluid into the ECS of the aircraft. In flight tests and ground tests, neither the level of any single 
chemical contaminant nor the sum of the concentrations of all the contaminants detected reached 
a concentration consistent with the CNS symptoms reported in recent incidents. In addition, 



DeNola, G., et. al. "Determination of Tricresyl Phosphate Air Contamination in Aircraft." 

Solbu, K. "Airborne Organophosphates in the Aviation Industry: Sampling Development and 
Occupational Exposure Measurements (No. 1068)." 

Liyasova, M., et. al. "Exposure to Tri-o-cresyl Phosphate Detected in Jet Airplane 
Passengers." 



105 



biological monitoring tests conducted on the blood and urine of incident pilots and ground 
personnel as well as test pilots were negative for exposure to hazardous levels of carbon 
monoxide or other toxic substances. 



106 



Appendix C: F-22 Combined Test Force Aircraft 
Instrumentation and Test Activities 



C.1 Objective 

This appendix summarizes the testing conducted at the F-22 Combined Test Force, 
Edwards Air Force Base, California, in support of the 2011 Safety Investigation Board research 
into the root cause of F-22 fleet hypoxia- like incidents that have occurred since 2008. 

C.2 Background 

Initial Air Force Flight Test Center (AFFTC) testing was accomplished from January to 
April 2011 using instrumented United States Air Force F-22 (specific aircraft serial numbers 
91-4007 and 91-4009). 

In December 2010, the Air Force Materiel Command (AFMC) Director of Air, Space, and 
Information Operations (AFMC/A3) granted a limited waiver to conduct On-Board Oxygen 
Generating System (OBOGS) testing up to 60,000 feet above mean sea level (MSL), which was 
higher than the 25,000 foot MSL restriction in place at that time. 

In January 201 1, temperature and pressure data were collected from four sensors installed 
at multiple locations in the Environmental Control System (ECS) of the F-22. Testing was 
performed with limited instrumentation in pursuit of ECS performance data and was executed as 
ride-along testing with other test programs. System performance was as designed with no 
deficiencies detected. 

In April 201 1, an oxygen concentration sensor and three additional pressure sensors were 
added to existing temperature and pressure sensors in the ECS of the F-22. Dedicated testing 
was executed with two different OBOGS units during maneuvers selected to reflect profiles of 
previous F-22 hypoxia-like incidents. System performance was as designed with no deficiencies 
detected. 

Follow-on OBOGS ground testing began in mid- July 2011 and flight testing began July 
25, 2011, and is described below. A total of 10 ground test and 20 flight test missions were 
executed as part of follow-on testing from July-October 201 1. 

C.3 Aircraft Instrumentation (July-October 2011 Testing) 

Aircraft 91-4009 was extensively modified with instrumentation presented in Table C-l 
(below), with emphasis on collecting data on potential breathing air contamination. Real-time 
contaminant measurement devices (ppbRAE) were used to record and display the time-stamped 
total volatile organic compound count. The aircraft data system was used to record data from the 
added ECS instrumentation. Telemetry was used for real-time monitoring of the aircraft data in 
the control room. Vacuum (summa) canisters were used to collect air samples from three 
locations: OBOGS input, air feeding the pilot's mask post Breathing Regulator Anti-G (BRAG) 
valve, and cockpit ambient environment. Desorption tubes (D-Tubes) were used to collect air 



707 



samples from these same three locations for post-flight detection of specific potential 
contaminants. Figure C-l below presents a diagram of the instrumentation installed. 



Sensor 


Method # Real-Time Data 




ppbRAE 


Detector 


3 


Total VOC + 
alarm (no CO) 


Plot of total VOC vs. 
time 


ECS 
Instrumentation 


Sensors in 

ECS 
ducting/lines 


9 


Temperature, 
pressure, PP0 2 
(telemetry) 


Temperature, 
pressure, PP0 2 


D-Tubes 


Collection via 
filtration 


6 


N/A 


Aldehyde ppb 


Aircraft 
SUMMA 


Air sample 
capture 


3 


N/A 


Amount of 97 VOCs + 
TICs 


Abbreviations: 

CO: Carbon Monoxide N/A: Not Applicable 

ppb: Parts per Billion PP02: Partial Pressure of Oxygen 

TIC: Toxic Industrial Compound VOC: Volatile Organic Compound 



Table C-l. Aircraft Instrumentation Added for Investigation. 



Instrumentation Location 




108 



CA Human Instrumentation 



The oxygen caution and warning system (OCAW) was used for real-time oxygen partial 
pressure data collection and real-time warning to the pilot of low oxygen concentration. The 
OCAW sensor was mounted at the base of the pilot's mask hose and was developed for this 
specific application. The human measurements are listed in Table C-2 (below). Pilot-mounted 
instrumentation is shown in Figure C-2 (below). 



Sensor 






Real-Time Data 


Post-Flight 






Lung 
SUMMA 


Air sample capture 


2 

(pre/post mission) 


N/A 


Amount of 
97 VOCs + 
TICs 


OCAW 


LED 2 sensor 


1 


PP0 2 


PP0 2 


Filter 


In development 


1 


N/A 


In 

development 


Chest 
Harness 


Chest sensor 


1 


N/A 


Heart data 

and 
respiratory 

rate 


Pulse-Ox 


Fingertip sensor 


1 


Blood 2 
saturation 


Blood 2 
saturation 


Blood 
Basic 


Sample 


8-10 vials 
baseline & post 


N/A 


Standard 
blood data 


Spirometry 


Exhale 


2 

(pre/post mission) 


N/A 


Lung 
function 


Urine Tox 


24-hour collection 


Baseline & post 


N/A 


Toxin 
presence 


Abbreviations: 

LED: Light-Emitting Diode 2 , Ox: Oxygen 

OCAW: Oxygen Caution and Warning TIC: Toxic Industrial Chemical 

Tox: Toxin, Toxicology VOC: Volatile Organic Compound 



Table C-2. Human Instrumentation. 



109 



Pilot-Mounted Sensors 



OC AW Pu Ise Ox / Heart Carbon fi Iter 




Figure C-2. Pilot-Mounted Instrumentation. 

C.5 Test Conditions (July-October 2011 Testing) 

The flight test profiles and test points from test plan AFFTC-TP- 11-30, F-22 On-Board 
Oxygen Generating System Phase II Ground and Flight Test are shown in Tables C-3 to C-5. 



Test 1 
Point 1 










1 


lOKft 
MSL 


0.9M 


As Req'd 


As Req'd 


a. Climb to 50Kft 

b. Engine thrust request (ETR): Idle, 
bank and pull to 3 g's 

c. Descend in idle to 45K ft 


2 


lOKft 
MSL 


1.2M 


As Req'd 


As Req'd 


a. Climb to 50Kft 

b. ETR: Idle, bank and pull to 3 g's 

c. Descend in idle to 45K ft 


3 


55Kft 
MSL 


1.5M 


As Req'd 


As Req'd 


a. Slow deceleration to 1M 


Abbreviations: 

A/S: Airspeed Ft: Feet 
K: Thousand M: Mach 



Table C-3. F-22 OBOGS Phase II Flight Test Profile A. 



110 



Test 
Point 












1 


5Kft± 
500 ft 
MSL 


0.9 ± 
0.05 
M 


MIL 


As Req'd 


a. Climb to 40K ft, maintain <50 AOC 

b. MIL-IDLE snap at top of climb (1 
minute of climb required) 

c. End run at or below 100 KCAS 


2 


18K ft ± 
500 ft 
MSL 


430 ± 

20 
KCAS 


As 
Req'd 


As Req'd 


a. Wind up turn (WUT) g (100% 
NzW), 120°-130° bank, continue turn 
through 90° of heading change 

b. Continue turn, -10° to -20° gamma 
select AB, g as required to capture 
duu-ddu i\laj inrougn z/u 

c. Wind-up turn g (100% NzW), full 
AB, pull to >36° alpha 

d. Unload, -20 to-30° gamma, full AB to 
capture 300-350 KCAS 

e. Repeat b, c, and d until 10,000 ft AGL 


3 


18K ft ± 
500 ft 
MSL 


430 ± 

20 
KCAS 


As 
Req'd 


As Req'd 


a. Line abreast (LAB) @ set range +3K ft 

b. Test will call for 45 9 check into chase 

c. Test turns to lock chase and calls out 
range 

d. Chase starts an easy turn into test 
and sets aspect 

e. Test call decreasing range and "test is 
on" at set range 

f. Floor: 5K ft AGL minimum, 
recommend 10K ft MSL 

g. Control room monitor 

h. Altitude - KIO if descend below floor 

i. OBOGS 

j. Traffic - KIO less than 5 nm (MSL = 
greater than floor - IK ft but less 
than25Kft) 
k. Reset: (after KIO or Terminate) 
1. Deconflict flight paths, then MIL 
power 

m. Accelerate to 350 KCAS a start climb 

on ref heading 
n. Chase move out to next set range 

+3Kft 


4 


18K ft ± 
500 ft 
MSL 


430 ± 

20 
KCAS 


As 
Req'd 


As Req'd 


a. LAB 6-9K ft 

b. Test will call for a 45° check away 

c. Test will call "Turn in, test is on" at 
3-5nm separation 

d. Floor: 5K ft AGL minimum, 
recommend 10K ft MSL 

e. Control room monitor 

f. Altitude - KIO if descend below floor 

g. OBOGS 

h. Traffic - KIO less than 5 nm (MSL = 
greater than floor - IK ft but less 



111 













than25Kft) 
i. Reset: (after KIO or Terminate) 
j. Deconflict flight paths, then MIL 

power 

k. Accelerate to 350 KCAS a start climb 

on ref heading 
1. Chase move out to next set range 

+3Kft 


5 


As Req'd 


As 
Req'd 


As 
Req'd 


As Req'd 


a. MIL-IDLE-MIL throttle transients, 
optional 


Abbreviations: 
AB: Afterburner 
Alpha: Angle of Attack 
Gamma: Flight Path Angle 
KIO: Knock it Off 
MIL: Military 
nm: Nautical Mile 


AGL: Above Ground Level 
AOC: Angle of Climb 
Knots Calibrated Air Speed 
LAB: Line Abreast 
MSL: Mean Sea Level 

NzW: Load Factor Normal to the Flight Path 



Table C-4. F-22 OBOGS Phase II Flight Test Profile E. 



Test 
Point 








^9H 




1 


40Kft 
MSLto 
5Kft AGL 


As 
Req'd 


As 
Req'd 


6±2 


a. Setupat40Kft, 25Kft,orl5Kft 

b. Set mixture switch as appropriate 
(AUTO or MAX) 

c. Ensure UPG is in appropriate 
configuration (connected or 
disconnected) 

d. Sustained-g turn until 5K ft AGL is 
reached or sufficient data are 
collected 

e. Repeat steps a-d as required 


Abbreviations: 

UPG: Upper Pressure Garment 



Table C-5. F-22 OBOGS Phase II Flight Test Profile G. 

C.6 Aircraft Configurations (July-October 2011 Testing) 

Eight aircraft configurations were ground and flight tested from July to October 2011. 
The configurations included the incremental addition of components from incident aircraft in an 
effort to "stack the deck" against this test aircraft and induce conditions under which symptoms 
of root cause might be detected. Configuration 8 was used to investigate the phenomena of 
reduced oxygen output while under g that was evident in data collected in the earlier 
configurations. The configurations are listed in Table C-6 and the flight dates are listed in Table 
C-7 (below). 



112 



Configuration 










Stress: 
Profile A 


Stress: 
Profile E 


Inv: 
Profile G 


1 


Baseline (low performing 
OBOGS) 










2 


nign-on consumption 
engine from Elmo 










3 


Engine from an incident 
aircraft at Elmo 










4 


Engine from an incident 

aircraft at Elmo 

w/ coiiapseo scavenge 

tube 










5 


engine Trom an incident, 
aircraft at Elmo w/ 
collapsed scavenge tube 
and incident BRAG 










6 


Config 5 + high 
performing OBOGS 










7 


Config 6, Mixture Switch 
in AUTO 




/ 


/ 




8 


Installed: post-BRAG 
NeoFox & pressure 
sensors 

Removed: incident 
engines, damaged 
scavenge tube, summas, 
RAEs 










Abbreviations: 

Auto: Automatic Config: Configuration 
Elmo: Elmendorf Air Force Base w/: with 



Table C-6. Aircraft Configurations and Flight Profiles. 



113 



Config 
No. 








Contaminate filter cockpit compatibility (ground test) 


7/13/2011 


Contaminate filter cockpit compatibility test with boot 
& CRU-122 (ground test) 


8/26/2011 


1 


Ground test 


7/16/2011 


Ground test 


//ZU/ZU11 


Ground test 


7/Z9/Z011 


r|i n Ll nvA^ilA A 

Nignt proTiie a 


//Zb/ZUll 


riignt proTiie m 


7 /^n/?m 1 


riignt proTiie t 


o/ Z/ ZU11 


z 


Ground test 


O //I 1 

o/4/ZUll 


riignt proiiie m 


o/c/9ni 1 
0/ D/ ZU± 1 


nignt rroTiie t 


o/ y/zuii 




Ground test 


O /1 ft /Oft1 1 

o/IU/ZUII 


riignt proiiie m 


q/1 1 /">ni 1 

O/ ±±/ ZUJ.1 


Flight profile E 


8/12/2011 


4 


Ground test 


8/15/2011 


Flight profile A 


8/16/2011 


Flight profile E 


8/17/2011 


5 


Ground test 


8/23/2011 


Flight profile A 


8/29/2011 


Flicjht nmfilo P 


O/ Jl/ £.isj.j. 


6 


Ground test 


9/1/Z011 


Flight profile A 


9/Z/Z011 


Flight profile E 


ft /o 1 

9/8/Z011 


7 


Ground test 


ft /O /Tft-1 1 

9/8/Z011 


Flight profile A 


ft /ft /ini ^ 

9/9/2011 


rl" La 1 _ r 

Flight profile E 


9/13/Z011 


8 


Ground test 


m/iQ /im 1 


Flight profile A 


10/18/2011 


Flight profile E 


10/19/2011 


OBOGS set to MAX flight profile G 


10/20/2011 


OBOGS set to A 3 flight profile G 


10/21/2011 


OBOGS set to MAX flight profile G 


10/24/2011 



r<aZ?fe C-7. Ground and Flight Test Dates. 

C.7 Results 

There were no indications of failures of the aircraft life support components or 
contamination to the pilot's air supply. 



114 



Appendix D: 

Human Systems Integration and the F-22's Environmental 
Control System (ECS) and Life Support System (LSS) 

During the early Advanced Tactical Fighter (ATF) development program (the precursor 
of the F-22 program) Human System Integration (HSI) analysts were chartered to focus on 
Manpower, Personnel, Training, and Safety. From 1989 to 1994, analysts from the Aeronautical 
Systems Division (ASD) HSI Office were collocated to the ATF Program Office. As a 
consequence of a heightened awareness of the manpower, usability, maintainability, safety, 
human effectiveness, and cost savings achievable by the application of human factor engineering 
methods, the analysts and program leadership were able to bring about changes representing 
different priorities and policies in program management decision-making. Engineering, human 
factors, manpower, personnel, training, and logistics were integrated. 

The HSI efforts within the ATF program focused on Air Force goals, including Air Force 
Specialty Code (AFSC) compression (5 AFSCs versus 15), reliability and maintainability 
objectives, reducing support equipment requirements, and reducing the logistics footprint. To 
achieve these goals, the analysts concentrated upon analysis of maintenance skills, reducing the 
required maintenance manpower, maintenance accessibility, the component maintenance 
concept, component self-diagnosis, trouble- shooting, training requirements, and improved engine 
performance, removal, and repair. As a result of their efforts, life cycle cost savings were 
estimated to be $780 million (M). Parts for the F-22 engine were reduced by 40%. Maintenance 
access to and around the ejection seat was improved. Support equipment was reduced by 75% 
less than legacy systems. 48 

Technical support of the efforts beyond the HSI technical capabilities embedded within 
the ATF System Program Office came from the Air Force laboratories and the ASD engineering 
offices in areas including: crew systems, life support systems, oxygen generation, propulsion, 
workload management, training methods and simulators, cockpit controls and displays, and 
human factors engineering. As a result of the ATF contract efforts, the F-22 pilot was given 
advanced personal protective equipment, integrated sensors, controls and displays, stealth 
technology, and sustained supersonic cruise. 

At this same time, acquisition policies were changing, diminishing the influence of 
proven military standards as well as national and international standards. Additionally, the 
workforce was downsized in response to acquisition reform initiatives. During the early 1990s, 
the ASD HSI Office manning was reduced to 21 positions. In 1994, prior to the developmental 
flight tests of the F-22, the HSI program office was disbanded due to funding and personnel 



Carr, L. "F-22 HSI Case Study." 



115 



reductions within ASD and other Air Force organizations that had provided personnel positions. 
The expertise required to perform the critical integration analyses became insufficient. 

Further atrophy of the then existing policies, and abandonment of military standards, 
occurred due to continued acquisition reform. In the period of 1999 to 2000, Air Force Research 
Laboratory (AFRL) personnel who had been supporting the development of performance 
standards, man-rating tests of the F-22 life support systems, and studies of altitude physiology, 
oxygen generation, and aviation occupational health and safety, including toxicology, were 
eliminated in a general AFRL reduction of funding and personnel. Note: See Appendix E of this 
report for details. 

The F-22 program did not initially intend to create a life support system to raise the 
fighter's altitude capability, but rather to utilize the inherent altitude protection capabilities 
afforded by partial-pressure garments for G protection developed by Boeing under an Air Force 
advanced development program, the Tactical Life Support System (TLSS), that was initially 
used. 49 However, the F-22 life support system was designed to provide protection for 
high-altitude flight operations, in-flight decompressions, and high-altitude emergency escape to 
altitudes in excess of 50,000 feet to meet unprecedented gains in Soviet tactical air power. 50 The 
partial-pressure ensemble designed for the F-22 was viewed as "get-me-down" protection. 51 Its 
short duration capability is mandated by the 70 mmHg pressure breathing required (70 
millimeters of mercury (mmHg), or about 1.3 pounds per square inch), which pushes blood 
peripherally, and slowly reduces cardiac output; this can cause dizziness and fainting. Thus, the 
G-suit is inflated to slow peripheral pooling and prevent these effects. 

From a total breathing air supply perspective that encompasses the ECS, as well as the 
life support equipment, some of the assumptions about the performance of the altitude protection 
system have proven to be based on incomplete data. For example, the understanding of the 
thermal management capacity of the F-22 aircraft ECS has proven to be limited. Excessive heat 
load from the mission avionics has caused the ECS to periodically shut down, resulting in 
disruption of the On-Board Aircraft Oxygen Generation System (OBOGS) inlet air from the ECS 
which in turn causes the oxygen generation system to shut down, thereby depriving the pilot of 
oxygen during those periods. Flight tests have been accomplished to define the causes and the 
duration of these ECS shutdowns. These disruptions of the OBOGS inlet air flow may lead to 
the release of breathing air contaminates within the OBOGS molecular sieve due to relaxing the 
inlet pressure to 22 psig, as demonstrated for carbon monoxide. 54 

At the time of the F-22 LSS development, the knowledge of the ability of the OBOGS to 
filter or to pass contaminates was limited to likely flight line contaminates such as water, carbon 



49 McGarvey-Buchwalder, D. T-22 Life Support System for High Altitude Protection." 

50 Neubeck, G. T-22 Concept of Operations above 50,000-ft." 

51 McGarvey-Buchwalder, D. T-22 Life Support System for High Altitude Protection." 

52 Morgan, T. "BRAG Valve Overview." 

53 Javorsek, D., et. al. "F-22 All Weather Fighter: Recent ECS Testing Results." 

54 Gordge, D. "Transient CO Assessment." 



116 



dioxide, and carbon monoxide. Organic and inorganic compounds were also explored by Ikels 
to develop general principles regarding the kinetic diameter of the molecules and their adsorption 
and desorption during the OBOGS pressure swing cycle, as well as their likelihood of finding 
their way through the crystal lattice of the zeolite bed into the breathing gas. At the time of this 
review, the database of molecules and compounds found in the F-22 ECS air that have been 
evaluated in terms of their ability to pass through the OBOGS into the breathing gas under 
various aircraft and OBOGS operating conditions has approached 300 molecules. 

It was also presumed that at altitudes above 50,000 feet, the use of positive pressure 
breathing, maximum 93% oxygen rather than the 99+% oxygen, and the partial pressure suit 
created by a counter-pressure vest and extended coverage G-suit would be adequate to protect 
the pilot from decompression sickness and rapid loss of consciousness. The initial decision to 
raise the altitude limit to 60,000 feet was based upon extrapolation from United States Air Force 
and other air forces' altitude research experiments under conditions of rapid decompression to 
50,000 feet. Tests conducted by the Air Force Armstrong Laboratory demonstrated that there 
was no statistical significance between oxygen concentrations of 99% during rapid cockpit 
decompression, which was the previous requirement, and oxygen concentrations from 93-95% to 
as low as 90% and 85% with dilution and non-dilution regulator settings, but the numbers of 
subjects were very limited. 56 

A second study that was conducted with one-second rapid decompressions (5 psi 
differential, or psid) to 46,000 feet, 52,000 feet, 56,000 feet, and 60,000 feet. 57 The Air Force 
TLSS ensemble was worn by the test volunteers. The TLSS demonstrated the effectiveness of 
the principle altitude and acceleration protection features of the crew-worn F-22 life support 
system. The TLSS provided: (1) a mask capable of sealing at high breathing pressure; (2) 
helmet assisted mask tensioning; (3) chest counter pressure equal to breathing pressure; (4) an 
extended coverage G-suit; (5) and a regulator capable of delivering breathing pressures for 
altitude up to 70 mmHg. Breathing pressures were 50 mmHg at 46,000 feet and 70 mmHg at 
each of the other altitudes. As with the original study, time at peak altitude was one minute, but 
the G-suit was inflated at peak altitude with positive pressure breathing. At least 13 exposures 
with male subjects were completed at each altitude. 

With the improvements TLSS provided, the physiological measurements during rapid 
decompressions to 60,000 feet with 93% oxygen were better than those seen in the original study 
at 50,000 feet using 100% oxygen and the standard oxygen system. Additionally, subjects who 
had participated in both studies reported that, when wearing TLSS during a 60,000 feet 
decompression, the level of protection subjectively felt much better than using the standard 
oxygen system at 50,000 feet. 



Ikels, K. "Effects of Contaminants on Molecular Sieve Oxygen Generators." 

O'Connor, R. "Use of Variable Oxygen Concentrations to 50,000 Feet." 

O'Connor, R., et. al. "Effect of Rapid Decompression to 60,000 Feet Using 94% Oxygen and 
Assisted Positive Pressure Breathing." 



117 



The actual maximum delivered oxygen concentration is a function of aircraft and cockpit 
altitudes, breathing load, ECS air characteristics, and OBOGS bay temperature, any of which can 
affect the concentration. 

To evaluate the performance of OBOGS in the F-22, as part of an investigation of 
operationally incurred hypoxia and hypoxia-like events, oxygen production tests were conducted 
to develop baseline data for the F-22 fleet. 59 One hundred twenty-five tests were conducted to 
measure oxygen concentration and OBOGS oxygen sensor error. Twenty retests were conducted 
to determine reproducibility of OBOGS performance. The tests were conducted at ground level 
with the OBOGS mixture switch set to MAX and the breathing rate was normal. One of the 
objectives of the tests was to identify OBOGS units that produced "outlier" performance. Note 
that OBOGS performance is improved at higher altitude, so these results may not be indicative of 
performance at reduced atmospheric pressures. 

The results of these tests demonstrated that the operational fleet OBOGS units produced 
an average oxygen concentration of 85.1% with a standard deviation of 7.7%. The OBOGS 
internal oxygen concentration sensor errors, with respect to a reference instrument, averaged 
0.5% from the reference, but the scatter of the measurements was large. The standard deviation 
was 10.9%). The threshold for a warning of oxygen generation failure was set at 10 psig to 
prevent a high probability of false F-22 ICAWS (Integrated Caution/ Advisory/Warning System) 
alarms. 

Man-rating tests of the OBOGS had been conducted by the Armstrong Laboratory in an 
altitude chamber at Brooks AFB at altitudes ranging from 10,000 feet up to 70,000 feet, 
unmanned at OBOGS inlet pressures of 35 and 80 psig. 60 Tests were performed in OBOGS 
AUTO and MAX modes. One test was conducted at an altitude of 10,000 feet with an OBOGS 
inlet pressure of 27 psig, outside the OBOGS operating specification for information gathering 
since lower pressures were not anticipated during normal ECS operations. Tests were then 
conducted with volunteer subjects wearing the contractor furnished F-22 LSS and also 
chemical-biological protection clothing configurations. The trials of the LSS consisted of 
breathing resistance evaluations, rapid decompressions, and tests of the Emergency Oxygen 
Supply (EOS) supply duration. Manned, one-second decompressions were completed over 5 psi 
differentials to final altitudes of 46,000 feet, 52,000 feet, 56,000 feet, and 60,000 feet. The 
OBOGS inlet pressures that were tested were 35 and 80 psig. The influence of lower OBOGS 
inlet pressures on oxygen concentration levels was not explored. 

The current F-22 breathing system does not measure the oxygen concentration between 
the Breathing Regulator Anti-G valve and the pilot's oxygen mask. An oxygen sensor has now 
been inserted in this position in an F-22 test aircraft, but the data are not available at the time of 
this writing. Other measurements were required, but the measurement techniques that have been 



McGarvey-Buchwalder, D. "F-22 Life Support System for High Altitude Protection." 

Hoog, S. "Safety Investigation Board OBOGS & Aircrew Flight Equipment to SAB Quick 
Look Study on Aircraft Oxygen Generation." 

Diesel, D., et. al. "Human Performance Testing of the F-22 Life Support System." 



118 



used have not proved to be completely adequate during the study. These measurements include 
key physiological state indicators, such as blood oxygen concentration and pulse rate, as well as 
accurate measurements of potentially hazardous air contaminates as a function of time. 
Measurement techniques used to detect contaminates have included swab samples taken at 
numerous aircraft and life support equipment surfaces and the use of summa canisters to sample 
air over varied time increments. These techniques are not capable of detecting short-duration, 
episodic releases of concentrated contaminates that might be released from the molecular sieve 
beds at low OBOGS inlet pressures. None of the tests measured periods of low OBOGS inlet 
pressure (other than during ECS shutdowns) that would have caused such episodic releases of 
contaminants. 

The original standards applicable to the F-22 oxygen supply system were: Air Standard 
61/101/1C, Minimal Protection for Aircrew Exposed to Altitude Above 50,000 Feet; Air 
Standard 61/101/6A, Minimum Physiological Requirements for Aircrew Demand Breathing 
Systems; and STANAG 3865, Physiological Requirements for Aircraft Molecular Sieve Oxygen 
Concentration Systems. To meet these requirements, the original F-22 LSS included a Backup 
Oxygen System (BOS) that would be activated automatically in event of oxygen supply failure to 
supply 93-95% oxygen to the pilot. The BOS was deleted from the LSS without integration of 
an automatic Emergency Oxygen System activation system as a result of a trade study. 61 The 
rationale for the elimination of the BOS and the recommended use of manual activation of the 
ejection seat mounted EOS Supply was described earlier in the Engineering Assessment section 
of this report. 

Judging that the science and technology base was adequate for the areas of altitude 
physiology, altitude protection equipment, oxygen generation technology, high-altitude life 
support systems, and toxicology, a major reduction in AFRL science and technology personnel 
in these specialties was directed. This action was based upon the assumption that the existing 
technologies were adequate, understood, and could be accessed through a Defense Technical 
Information Center contractor analysis capability (i.e., the Human System Integration 
Information Analysis Center). The eventual loss of this Information Analysis Center services 
capability due to subsequent funding reductions deprived the USAF, other Services, and industry 
of the existing HSI tools, processes, lessons learned, and the foundation science and technologies 
for their application in the analysis of issues within other system acquisition programs, as well as 
diagnosis of human systems integration problems encountered during F-22 flight operations. 



McGrady, M., & Holmdahl, M. "LSS OBOGS Standby Oxygen Trade Study 
(L-8935-92-MBM-013)." 



119 



(This Page Intentionally Left Blank) 



120 



Appendix E: 

Effect of Funding and Personnel Reductions: Human 
Performance Competencies 

EA Historical Background 

In the decade following World War II, the method to store breathing oxygen as liquid 
oxygen was developed for fighter aircraft to replace gaseous oxygen stored in steel cylinders 
used throughout the war. Gaseous oxygen flowed from a liquid oxygen converter through a 
pressure demand regulator where the oxygen was usually diluted with cabin air. The United 
States (US) Air Forces developed a vast experience in the operational use and reliability of liquid 
oxygen storage, pressure demand regulators, and various aircrew masks. The weight and size 
advantage of liquid oxygen systems led to their use in nearly all high-performance combat 
aircraft. 

However, liquid oxygen systems have significant disadvantages. The risk of 
contamination of the breathing oxygen by the inclusion of toxic compounds such as various 
oxides of nitrogen and carbon as well as hydrocarbons during manufacturing exists. Precautions 
must be taken to assure that moisture is excluded from the system to avoid the development of 
ice in the pipes and valves by the low temperatures generated by the expansion of gas when the 
oxygen flows within the system. Charging hoses and connectors must be purged with dry gas 
before use. Although the risk is very low, fuels, oils, fine particles of metal, and other materials 
that are combustible in 100% oxygen must be avoided in the charging components of both stored 
gas systems as well as liquid oxygen systems to prevent fire and explosion. 62 

Transferring liquid oxygen from its manufacturing plant to the aircraft liquid oxygen 
converter is an expensive process in terms of cost, ground equipment, and manpower. Only 
about 10 to 15% of the liquid produced by the plant reaches the aircraft oxygen converter. The 
rate of loss of oxygen from the converter, approximately 10% in 24 hours, makes recharging 
essential. 63 

The proven, though very low, risk of fires and explosions occurring in gaseous and liquid 
oxygen production plants, and during recharging aircraft oxygen as well as the need to separate 
re-arming and recharging of oxygen stores during rapid turn-around of aircraft in war have 
contributed to on-board oxygen generation becoming the method of choice for advanced 
high-performance combat aircraft. 64 



United States Department of Defense. "Design and Installation of Liquid Oxygen Systems in 
Aircraft, General Specification for (MIL-D-1 9326G)." 

Ernsting, J. "Conventional Aircraft Oxygen Systems." 

Ibid. 



121 



The concept of on-board generation of breathing oxygen originated in the early 1960s as 
a result of the National Aeronautics and Space Administration's (NASA) interest in long 
duration space flight. There was a natural interest in this concept from the closed-cycle 
applications in spacecraft to semi-closed loop, and eventually, open loop applications in aircraft. 
The early investigations by the industry and the military air forces laboratories in the United 
States and the United Kingdom brought together multi-disciplinary teams of engineers, chemists, 
altitude physiologists, and aviation physicians. Oxygen generation technologies that were 
dependent upon a supply of air, and several that were air independent, were explored. Three 
systems, two air-supply dependent, advanced to the flight- test phase. By 1978, all were 
abandoned for various operating limitations with the exception of a pressure swing adsorption 
(PSA) concept. 

The behavior of synthetic crystal zeolite and its performance in molecular sieves was 
well known. It could be tailored in terms of its structure, composition, and properties. In 1977, 
Litton offered a molecular sieve oxygen concentrator using zeolite capable of delivering 95% 
oxygen. 

Prior to about 1976, an oxygen concentration of less than 99% would not have been 
sufficient. However, there was a successful demonstration of the protection of volunteer subjects 
wearing the advanced development Tactical Life Support System (TLSS) during rapid 
decompression at 60,000 feet. 65 The TLSS equipment provided assisted positive pressure 
breathing up to 70 millimeters of mercury. 

After review of the results of research and advanced development efforts to provide 
oxygen generation using other chemical processes, the PSA molecular sieve process concept 
emerged as the clear choice. The PSA molecular sieve demonstrated the advantages of 
simplicity, small size, low weight and power requirement, minimal cost, and broad applicability 
to aircraft of crew sizes up to ten. Its principle disadvantage (i.e., producing less than 100% 
oxygen) can be overcome by the relatively simple expedient of adjusting the pressure delivery 
schedule of the breathing regulator, when this is required for hypoxia protection. 66 

Tests were conducted by the United States Air Force (USAF) School of Aerospace 
Medicine and at the Naval Air Development Center to characterize the performance of a 
two-person-capacity molecular sieve oxygen generation system under simulated flight 
conditions. 67 The US Navy conducted demonstration flight tests of the concentrator using the 
EA-6B aircraft, and then initiated the development of a system for the AV-8B aircraft for 
operational test and evaluation from 1977 to 1980. 68 ' 69 The USAF modified the F-16 to 

70 

incorporate on-board oxygen generation systems. 



O'Connor, R., et.al. "Effect of Rapid Decompression to 60,000 Feet Using 94% Oxygen and 
Assisted Positive Pressure Breathing." 

Miller, R., & Ernsting, J. "History of Onboard Generation of Oxygen." 

Miller, R., et. al. "Molecular Sieve Generation of Aviator's Oxygen: Performance of a 
Prototype Under Simulated Flight Conditions." 

Manatt, S. "Onboard Oxygen Generation Systems." 



122 



As a result of a briefing on the On-Board Aircraft Oxygen Generation System (OBOGS) 
advantages and flight test results, the Commander of the Air Force Systems Command issued a 
message in February 1983 to the Commander of the Aeronautical Systems Division stating: 

OBOGS has the potential to become the Air Force aviator's breathing gas system of the 
future. This system offers operational advantages, which should free the Air Force from 
dependence on liquid oxygen and its attendant logistics and safety constraints. It is time 
to step out with the OBOGS system. 

The Aeronautical Systems Division, as well as the US Army and US Navy, subsequently 
launched engineering development programs for molecular sieve oxygen generation systems for 
the air vehicles described earlier in this Aircraft Oxygen Generation Study Report. 

E.2 The Science and Technology Base for Oxygen Generation 
Systems 

The knowledge and experience of the scientists and engineers of the Air Force, Army, 
and Navy Laboratories and Test Centers have been essential in the development, test, and 
evaluation of molecular sieve oxygen generation systems. However, these scientists and 
engineers have also recognized that there were sources of contaminates that could adversely 
affect the performance of the oxygen generator and the quality of the air provided to aviators. 
Examples include: contaminates in the ambient air such as exhaust from other aircraft, moisture 
that may accumulate in molecular sieve bed, toxic gases ingested by the engine during firing of 
munitions, or chemical/biological attack. Another example is the infiltration of aircraft 
lubricants, hydraulic fluids, and jet fuel into the engine bleed air, which then undergo pyrolysis 
and/or decomposition upon exposure to high temperature, 72 becoming potentially toxic and 
entering the cockpit and also the on-board oxygen generation system. 

The extent to which such contaminates would be adsorbed on the molecular sieves 
depend greatly upon the polarity and dipole moment of the contaminate molecule, as well as its 
size, shape, and degree of unsaturation. 73 The molecular sieves currently used for separating 
nitrogen from oxygen have pore diameters of 4.2 Angstrom (type 5A molecular sieve) or 7.4 
Angstrom (type 13X molecular sieve). 74 



Routzahn, R. "An Oxygen Enriched Air System for the AV-8A Harrier (NADC-81 198-60)." 

Horch, T., et. al. "The F-16 Onboard Oxygen Generating System: Performance Evaluation 
and Man Rating (USAFSAM-TR-83-27)." 

Schroll, D., & McGarvey-Buchwalder, D. "Molecular Sieve On-Board Oxygen Generating 
System (OBOGS) Technical Assessment." 

Paciorek, K., et. al. "Fluid Contamination of Aircraft-Cabin Air and Breathing Oxygen 
(SAM-TR-79-34)." 

Ikels, K. "Effects of Contaminants on Molecular Sieve Oxygen Generators." 

Ikels, K., & Miller, G. "Molecular Sieves, Pressure Swing Absorption, and Oxygen 
Concentrators." 



123 



Extensive research was initiated within the Air Force Armstrong Laboratory to evaluate 
the effects of potential contaminates. These research efforts were focused on the effects of 
water, carbon dioxide, carbon monoxide, organic compounds, and inorganic compounds. 
Chemical warfare agent effects were studied in a joint United States - United Kingdom program 
as early as the 1980s. 75 

E.3 The Search for Efficiencies within the Department of Defense 
Research Establishment 

In the background of these research efforts, the Packard Commission's Blue Ribbon 
Panel was studying means to operate the Department of Defense (DoD) in a more efficient and 
economical manner. In June 1986, the Packard Commission issued its final report, A Quest for 
Excellence, proposing sweeping reforms to improve efficiency. President Reagan then signed 
National Security Decision Directive 219, directing implementation of the major 
recommendations of the Packard Commission. The Goldwater-Nichols Department of Defense 
Reorganization Act was signed into law that same year. 

Efforts were undertaken to consolidate some military laboratory research functions under 
initiatives such as the Armed Services Biomedical Research Evaluation and Management 
(ASBREM) committee. ASBREM joint service agreements were, within the next five to six 
years, effective in these efforts. Chemical and Biological Warfare and Defense research was 
consolidated under the Army as the lead service. Thermal Physiology and Blast Effects 
Research was consolidated under the auspices of the Army Soldier Systems Center, Natick, 
Massachusetts. Army Toxicology Research personnel and facilities and Biodynamic Research 
facilities were collocated with the Air Force Aeromedical Research Laboratory at 
Wright-Patterson Air Force Base (WPAFB) and the Naval Health Research Center Detachment 
already collocated at WPAFB. Air Force, Army, and Navy research efforts on the biological 
effects of directed energy were consolidated at Brooks AFB, Texas. The Crew Technology 
Division of the Air Force School of Aerospace Medicine at Brooks AFB took the lead in the area 
of high altitude physiology and oxygen generation technology. 

In 1989, Congressional representatives complained that the Services were dragging their 
feet in supporting management reforms initiated by the Packard Commission and the 
Goldwater-Nichols Act. President Bush directed the Secretary of Defense to draft a plan to look 
at ways to improve management (with fewer employees) and organizational efficiency in DoD. 
The goal was to devise a strategy to implement sweeping reforms proposed in the Packard 
Commission's report. Later that year, the Secretary of Defense appointed special groups to 
develop research and development strategies. 76 The Office of the Secretary of Defense and the 
Services established Project Reliance in 1990. The objective of this initiative was to reduce 
duplication across the Services and improve coordination and integration. 



Ikels, K. "Effects of Contaminants on Molecular Sieve Oxygen Generators." 

Defense Science Board. "Report of the Defense Science Board Task Force on Research 
and Development Strategy for the 1990s (1990 Summer Study Volume 1, Executive 
Summary)." 



124 



In that same year, thirteen of the Air Force research laboratories were merged into four 
(the Armstrong, Phillips, Rome, and Wright Laboratories). The Armstrong Laboratory was 
formed from the laboratories and the USAF School of Aerospace Medicine that reported to the 
Human Systems Division. The Navy consolidated its technical infrastructure into four Warfare 
Centers. In 1991, the DoD-initiated, congressionally approved, Base Realignment and Closure 
(BRAC) actions led to the disestablishment and consolidation of management of nine Army 
laboratories under one command, and leading to the creation of the Army Research Laboratory. 
Similarly, the 1993 BRAC and the 1995 BRAC disestablished and transferred functions of the 
US Army's Fort Belvoir Research and Development Center and the Aviation Troop Command. 

In order to provide a long-term vision for the Air Force research laboratories, the Air 
Force Scientific Advisory Board initiated a study. 77 The study, entitled New World Vistas, 
identified examples of Core Technologies, which did not include human systems or human 
performance technologies. Critical Technologies for the future were identified, but only the 
technology of Modeling/Simulation/Training intersected the human systems/performance 
domain. A six-point strategy for research and development investment was recommended. The 
highest priority recommended was the development of Breakthrough Technology from 
investments in Research (6.1), Exploratory Development (6.2), and Independent Research and 
Development. Specific budget recommendations with offsetting reductions were also 
recommended, some presuming that industry would carry on research and development where 
the investments by the government laboratories were eliminated or reduced. 

In 1996, the National Defense Authorization Act directed the DoD to develop a 5-year 
plan and to set forth specific actions needed to "consolidate the laboratories and test and 
evaluation centers." The Secretary of Defense was to submit an initial plan to Congress no later 
than May 1996. 

A single plan called Vision 21 was developed. The plan identified three key pillars in 
accomplishing the desired laboratory reform. These were: 

• Reduction of infrastructure costs with emphasis on high-maintenance and inefficient 
facilities while retaining critical capabilities. 

• Restructuring resulting from improved processes and cross-service reliance. 

• Revitalization of key laboratories with an emphasis on critical technologies. 

Vision 21 played an important role in the Air Force's decision to continue to overhaul its 
laboratory infrastructure. The Air Force initiated a plan to reconfigure and streamline its 
laboratory structure to produce a more integrated and cost-effective operation. This action 
ultimately led to the decision in 1996 to reorganize and consolidate Air Force research resources 



United States Air Force Scientific Advisory Board. "New World Vistas: Air and Space Power 
for the 21 st Century - Summary Volume." 

United States Department of Defense. "Vision 21: The Plan for 21st Century Laboratories 
and Test and Evaluation Centers of the Department of Defense - Report to the President and 
Congress." 



125 



by establishing a single laboratory, the Air Force Research Laboratory (AFRL). 

AFRL was activated in 1997. 79 AFRL was organized into the following technology 
directorates: Air Vehicles, Space Vehicles, Information, Munitions, Directed Energy, Materials 
and Manufacturing, Sensors, Propulsion, and Human Effectiveness. The Air Force Office of 
Scientific Research, which supports research in academia as well as within the AFRL technology 
directorates, also reported to AFRL. 

E.4 Air Force Research Laboratory Major Funding and Personnel 
Reductions 















FY98 PB 


$1,264 


$1,312 


$1,378 


$1,412 


$1,457 


FY99 APOM 


$1,012 


$1,012 


$1,085 


$1,108 


$1,132 


Delta 


-$252 


-$300 


-$293 


-$304 


-$325 



Table E-l. USAF Science and Technology Budgets for Fiscal Years (FY) 1999-2003. 
Note: Dollars in millions ($M) 

The creation of AFRL was intended to create efficiencies by streamlining its organization 
and reducing the management and support staffs of the four laboratories. Funding savings were 
to be used to revitalize the laboratory and its highest priority programs. However, shortly after 
the Laboratory was established, additional large funding reductions compared to the FY98 
President's Budget (PB) were levied upon AFRL in the FY99 Amended Program Objective 
Memorandum (APOM) Science &Technology (S&T) Budget as shown in Table E-l above. 
Dollars are in millions. 

The S&T funding that had been allocated to the Armstrong Laboratory was reduced from 
$136M in FY96 to $82M (a reduction of 39.7%) in FY99. 

The following criteria were used in implementing the AFRL research and development 
program reductions: 

• Eliminate or reduce selected activities. 



Chait, R. "Perspectives from Former Executives of the DOD Corporate Research 
Laboratories." 



126 



• Work all eliminations/reductions vertically within the S&T budget , i.e., reduce the 
(normally) temporally-sequenced Basic Research, Exploratory Development, and 
Advanced Development budgets. 

• Criteria to be used: 

o Support of the Air Force "Global Engagement" strategy. 

o Uniqueness to the Air Force. 

o Science and Technology portfolio balance. 

o Maintenance of critical mass and quality of research personnel and facilities, 

o Effect on reimbursable (leveraged) funding. 

• Include both the programs and people associated with the recommended budget cut 
areas. 

The research and development program impacts that are pertinent to the subject of this 
Aircraft Oxygen Generation (AOG) Study were: 

• Aircrew Physiology Research was eliminated. 

o High Altitude Protection research was to end. 
o Spatial Disorientation research was stopped, 
o Aircrew Fatigue research was eliminated. 

• Aircraft Oxygen Research was eliminated. 

o The Multi-Mission advanced development program was canceled, 
o The cooperative program with NASA was terminated. 

• The Air Force component of the Tri-Service Toxic Hazards program at 
Wright-Patterson AFB was initially eliminated. 

o Reprogramming funds within the Human Effectiveness Directorate restored the 
half of the Toxic Hazards program that addressed occupational toxicology versus 
environmental toxicology. 

o Army personnel were eventually withdrawn from the US Army toxicology unit 
collocated at Wright-Patterson AFB. 

• S&T funding for the Aerospace Medical Research being conducted by the 
Aeromedical Directorate of the Armstrong Laboratory and the USAF School of 
Aerospace Medicine was eliminated. 

o Aircrew physical and medical standards development were stopped. 

The Aeromedical Directorate of the Armstrong Laboratory and the USAF School of 
Aerospace Medicine, including 502 positions which were funded by the Defense Health 
Program, were transferred from AFRL to the Human Systems Center at Brooks AFB. 



127 



The Armstrong Laboratory organization was reduced from six directorates to one 
directorate, the Human Effectiveness Directorate. Twenty-nine divisions were reduced to six 
divisions and 26 branches. 

Losses of personnel authorizations that resulted from the elimination or reduction of 
Science and Technology Programs and the removal of the Defense Health Program components 
from AFRL are shown in Figure D-l. 



1800 
1600 




Sep-96 Oct-97 Apr-98 May-98 Sep-98 Sep-99 Sep-00 
□ Officers □ Enlisted □ Civilians 



Figure E-l. Losses of Military Officer, Enlisted, and Civilian Personnel Authorizations 
During the Period from September 1996 to September 2000. 

A reduction in the AFRL Human Effectiveness Directorate personnel amounting to 44% 
of the directorate's S&T workforce was accomplished over the period of FY99 through FY00. 

There were many hard decisions made to accomplish the reductions to the Human 
Effectiveness Directorate. Additional factors influencing the decisions included: 

• The Air Force was willing to accept a higher risk in the application of the human 
technologies. 

• Aircraft cockpit design technologies, environmental protection research, and life 
support equipment, such as emergency escape systems, were considered mature and 
future research and development could be accomplished by industry. 80 

• The USAF Scientific Advisory Board had recommended that human augmentation 
technologies and human systems automation research were the highest priorities in 
order to reduce future Air Force personnel requirements. 81 



United States Air Force Scientific Advisory Board. "New World Vistas: Air and Space Power 
for the 21 st Century - Summary Volume." 



128 



• Some of the human performance technologies were considered to be "soft sciences" 
where the return on investment was not easily quantified. 

• Manpower and Personnel research was eliminated despite high quality scores from 
the Air Force Scientific Advisory Board — requirements and funding for the 
technologies by the Air Force using organizations were insufficient to support the 
envisioned benefits. 

• Tri-Service research agreements were not protected from funding and personnel 
reductions. 

E.5 Human Performance Technologies Application 

The application of the crew systems technologies, analysis tools, military standards, and 
design guidance developed by the Human Effectiveness Directorate hinges to a large extent upon 
the Air Force acquisition engineering organizations and, to a more focused extent, upon the 
practice of Human Systems Integration (HSI) within the Air Force and among Air Force weapon 
system contractors. Unfortunately, the function and benefits of HSI are not universally 
understood within the Air Force system acquisition community or its contractors. Its central role 
is frequently thought of as "human factors engineering." 

In the course of this AOG Study, the Panel was referred to Air Force Lieutenant Colonel 
Anthony Tvaryanas, a graduate of the Naval Post Graduate School with a doctorate degree in 
Human Systems Engineering, to define and clarify the importance of HSI in the development of 
weapon systems. As a result of our interview (A. Tvaryanas, personal communication, March 
29, 2012), he briefly described HSI as: 

A systematic process for identifying, tracking, and resolving human-related issues 
ensuring a balanced development of both technologies and human aspects of 
complex systems. In order to ensure that all human-related issues are considered, 
the DoD categorizes them into several main areas or domains: human factors 
engineering, manpower, personnel, training, system safety, occupational health, 
personnel survivability, and habitability. A core principle of HSI is the necessity 
for those developing, acquiring, and operating systems to maintain a holistic 
perspective on these domains. No one domain should be considered in 
isolation — rather, they need to be related to each other as any decision in one 
domain can easily impact multiple other domains. 

HSI is dependent upon, and is executed through, a disciplined systems engineer 
process. In the absence of the latter, the former will be ineffective. Both 



United States Air Force Scientific Advisory Board. "New World Vistas: Air and Space Power 
for the 21 st Century - Summary Volume." 

Erickson, J., & Zacharias, G. "Report on Human-System Integration in Air Force Weapon 
Systems Development and Acquisition (SAB-TR-04-04)." 



129 



processes seek to satisfy system stakeholders by incrementally growing system 
definition and development through a series of risk-driven decision milestones. 
Thus, they increase the likelihood of — but (importantly) cannot guarantee — 
project success. 

I will also emphasize the following specifically for the F-22 case: HSI is not 
synonymous with human factors engineering or environment, safety, and 
occupational health (ESOH), just as systems engineering is not synonymous with 
electrical or mechanical engineering. All are distinct disciplines, but HSI and 
systems engineering are unique in that they require breadth of knowledge (and 
perspective) over depth of knowledge. Thus, if one is looking for a deep 
understanding of the function of OBOGS, the HSI practitioner is not the 
appropriate POC [Point of Contact] — that would be the life support engineering 
and ESOH functions. 

The first prototype Air Force HSI organization was created at the Aeronautical Systems 
Division (now the Aeronautical Systems Center) in 1981 in response to a report saying, 
"Effectiveness of US Forces can be increased through improved weapon system design," citing 
adequate Manpower, Personnel, and Training analyses as a shortfall. This finding was 
reinforced by similar findings by the Defense Science Board and then in 1985-86 by an Air 
Force Functional Management Inspection. This issue was further emphasized by Congressional 
action requiring manpower requirements to be submitted for systems at Acquisition Program 
Milestone I and II decision points. The Secretary of Defense directed that the topic be expanded 
to include Safety. The HSI organization was established at the Aeronautical Systems Center 
(ASC) as the prototype with the intention to place similar organizations at each product center if 
proven. Manpower and funding for the organization was provided by Air Training Command 
and Air Staff sources including: 15 from Air Training Command, 13 "Palace Acquire" positions 
from Air Force Deputy Chief of Staff for Personnel, four from Air Force Procurement, four from 
the Air Force Military Personnel Center, and two administrative positions from ASC. 

The HSI program was successful in supporting the Advanced Tactical Fighter program, 
which was to develop the F-22 fighter. However, the HSI support to all ASC program offices 
was reduced and then eliminated by July 1994 due to Air Force-wide funding and personnel 
reductions occurring in the early 1990s. 

The disestablishment of the prototype office occurred three years before the first flight 
test of the F-22 fighter. The HSI analysts had successfully addressed the integration of 
Manpower, Personnel, Training, and Safety aspects of Systems Engineering for the F-22. 
However, the HSI analysts did not have, nor were they intended to have, the technical skills to 
evaluate the adequacy of the pilot breathing system or the environmental control system. The 
Air Force engineering organization within the Aeronautical Systems Center and the Air Force 
Laboratories provided these skills (Personal Communication, D. McGarvey-Buchwalder, 
September 2011). 

Efforts to reconstitute the HSI function in the late 1990s under the Human Systems 
Center were unsuccessful. In 2001, the commander of the USAF School of Aerospace Medicine 
asked the Air Force Surgeon General (AF/SG) to request the Air Force Scientific Advisory 



730 



Board (SAB) to study the requirement for Human Systems Integration. At the request of the 
Chief of Staff of the Air Force, the SAB then conducted a study. 83 The SAB reviewed current 
policies and practices (Air Force, DoD, and other Services) and collected inputs from key 
stakeholders to identify any shortfalls in current HSI practices. The SAB task also included 
assessment of the potential impact of HSI trends requiring change for the future and to 
recommend improvements in HSI policy, requirements, technology, and processes. 

The SAB HSI Study final report concluded: 

• HSI planning and execution on Air Force programs is hampered by lack of 
institutional support. 

• Definitive, Air Force-wide policy and design guidance for HSI implementation is 
required. 

• Senior-level organizational focus, oversight, and long-term advocacy must be 
provided. 

• HSI education and training for program managers and acquisition professionals are 
required. 

• Meaningful, quantifiable requirements for human performance must be developed. 

• Required demonstrations of HSI effectiveness should be required at program 
milestones. 

The SAB report states, 'The Air Force should take steps to assure more effective 
collaboration between AFRL Human Effectiveness and Information Directorates and their 
counterparts at the Air Force product centers. AFRL should undertake focused S&T initiatives 
to address gaps identified in cognitive engineering, human behavior modeling, and system 
engineering tools." (Note: The Human Effectiveness Directorate had conducted human system 
engineering research, been responsible for the development of HSI tools, and supported the 
Human Systems Integration Information Analysis Center for all the Services.) 

Furthermore, the SAB report indicated, 'The Air Force should also request (in 
cooperation with the other services) DoD and Joint Services policy changes that will benefit all 
warfighters. These changes should include elevating crew systems to a higher level in DoD 
Work Breakdown Structure guidelines, incorporating HSI as an element of the DoD 
Architectural Framework, and expanding the Joint Services Specification Guide HSI provisions 
to address non-aircraft systems." This has not been accomplished within the Air Force, but it is 
at the discretion of the system program manager. 

The AF/SG tasked his staff and 311 Human Systems Wing at Brooks AFB to develop a 
proposal for the Air Force HSI program. In 2006, the proposal was presented to the Air Staff 
and approved for implementation under the Air Force Vice Chief of Staff. The AF/SG agreed to 
fund the program for the first five years with line funding to be provided thereafter. A Joint 



Erickson, J., & Zacharias, G. "Report on Human-System Integration in Air Force Weapon 
Systems Development and Acquisition (SAB-TR-04-04)." 



131 



Service HSI Steering Committee was also formed in 2006. The Air Force HSI program was 
expanded to encompass the technical domains of Manpower, Personnel, Training, Environment, 
Safety, Occupational Health, Survivability, Habitability, and Human Factors Engineering to 
mirror the HSI domains of the other Services. 

Congressional direction was received for all Services to provide HSI reports. The 
Congress also directed Office of the Undersecretary of Defense (Acquisition, Technology, and 
Logistics) to take ownership of HSI in conjunction with its acquisition/sy stems engineering 
oversight role. 

The USAF HSI Office then funded and placed HSI analysts at five Major Commands to 
assist in requirements and program analysis. AF Materiel Command (AFMC) established HSI 
strategic responsibility within the Systems Engineering Division (AFMC/ENS) of the AFMC 
Directorate of Engineering and Technical Management (AFMC/EN). 

In 2008, the HSI organization, along with the USAF School of Aerospace Medicine at 
Brooks AFB, was transferred from the 311 th Human Systems Wing to the 711 th Human 
Performance Wing (HPW) of AFRL at Wright-Patterson AFB. The HSI analysts remained at 
Brooks AFB until 201 1, when their 31 positions were transferred to the 71 1 th HPW at WPAFB. 
Only two of the analysts moved to WPAFB, creating a major shortfall in HSI education, training, 
and experience. 

An HSI Implementation Plan was approved by the AFMC Commander in 2011. 
However, the AF HSI Office and AFMC budget submissions were not approved under the line of 
the Air Force Program Objective Memorandum process. Although line funding is more 
appropriate for the HSI role in its engineering development role, the AF/SG agreed to continue 
funding the HSI organization at the 711 th Human Performance Wing (31 positions) using 
Defense Health Program funding (contained within DoD Major Force Program 8) funding in 
consideration for its consultation role. Line funding for the AF HSI Office (two positions plus 
five contractors) has been promised for 2013. 

E.6 Summary 

This Study found that the elimination of funding and personnel in the areas of altitude 
physiology, altitude protection, and oxygen generation systems research, and the reduction of 
occupational toxicology research have contributed to a significant reduction of the AFRL 
scientific and technical competencies required to diagnose, identify, and solve the life support 
system problems that exist in the F-22 fighter. The elimination of research on the influence of 
contaminates on the quality of the breathing gas produced by the OBOGS in its early stages has 
recently resulted in considerable time and expense to the F-22 program to expand the required 
technical knowledge. Ironically, at the time of the elimination of oxygen generation research, a 
PSA molecular sieve that incorporated a second carbon-based sieve was under development that 
would produce 99% oxygen and improve the filtering of contaminates by the OBOGS. 84 



Miller, G. "A 99% Purity Molecular Sieve Oxygen Generator." 



132 



After the abolishment of the first HSI office at ASC in 1994, the subsequent history of 
the Air Force HSI program illustrates the difficulty of completely reconstituting, and even 
expanding, the scope of a competency during periods of change in Air Force acquisition policies, 
budget considerations, closure of bases, and personnel reductions. The recent movement of the 
HSI organization, with the loss of the majority of the HSI practitioners, has resulted in the need 
to recruit and train a new workforce and to reestablish the benefits of HSI within system 
acquisition programs. Creating a robust HSI competency will be very difficult without more 
adequate and appropriately aligned funding (DoD Program 6 (specifically 6.4, Advanced 
Component Development and Prototypes) rather than Program 8), as well as strong institutional 
advocacy and priority. 

Initial steps to reconstitute the appropriate competencies required to address the F-22 
problem, as well as prevent potential problems in other existing or future aircraft programs, is 
currently underway by collaboration among and through: 

• Components of the AFRL 71 1 th Human Performance Wing (the Human Effectiveness 
Directorate, USAF School of Aerospace Medicine, and the Human Performance 
Integration Directorate), 

• AFRL's Propulsion Directorate, Sensors Directorate, Materials and Manufacturing 
Directorate, 

• Naval Medical Research Units technical support, and 

• Technical consultation with NASA. 

However, development of adequate research cadres, more capable sensors, test facilities, and 
modeling and simulation capabilities will require more personnel and funding resources than 
appear to this AOG Study Panel to be available at this time. 



733 



(This Page Intentionally Left Blank) 



134 



Appendix F: F-22 Program Schedule 



FY 36 87 88 39 90 91 92 93 94 95 96 97 98 99 00 01 



Milestone [ {750 a7e) 
Dem/Val Start M 



Milestones 



Demonstration / 
Validation 



Engineering and 
Manufacturing 
Development 

Production 
Representative Test 
Vehicles 




Production Quantities 



Sustiimment 



Bed Down 



4 Major Aire raft Review 



^ r.l i usione 
EMDStart 



sue 1 1 [648 ate) 



02 03 04 05 06 07 OS 09 10 11 12 13 
^ ot&e Phase 1 [OCt 03] 



^Bottom Up Review |442 a/c) 



YF-22 First Flight 9/90 



^ ICT&E Stan [Apr 04} 

^ frf Decision (Mar 05) 
+FQT&E complete (Nov 
4>0C | Dec 05) 



/05| 

avfl7b Inc ? 



. LRIP 

DAi (»9a/c| 



^ DAE [2B5 aiC] 
♦ 



^ FOT&E(2) (May07 r lnc2 
FOCfDecOT) 

^LoMOOCOSRi 

♦ FOT&E{3) 
inc 3.1 



First FtghflSNO 



r First Flight ENID 



9 FlightAircraft 

(1 Static and 1 Fatigue Aircraft) 



T&E/ 
OT&E 



DAB (1«5afc) 
POD 793- 
llffta Cost PoiSion fcirthtr 
reduced production esJim«ta to 1 77; 
MY savings & Lot 10 allowed total 
production to reach 1H5 





PRTVI 


2 





PRTV II 



MYP 



Lot 



Lot Delivery Quantities 
10 13 21 22 24 24 2Q 20 20 4 

1 23456789 10 



" Lot 6 dUinrJty Includes. RTA 



Long Term PBL 



Figure F-l. F-22 Raptor Program Schedule Showing Acquisition Milestones and Phases, Major 
Program Events, and Aircraft Lot Deliveries from Fiscal Year (FY) 1986-2013. 



135 



(This Page Intentionally Left Blank) 



136 



Appendix G: 



Policies, Plans, and Procedures: Interviewees 




ame & Position 



_ 





Air Force Materiel Command Standardization 
Officer 

Former Chief of Aeronautical Systems Center 

( A a n (\ Air* lnr\TT»p» T? p»cp»QT"r* n T n T^nfii tr\v\/ 
JL- J CLLLKX /*. 1 1 .TUIUC JVCoCdlUll l^/CXUKJL dlKJL y 

Engineering Standards Office. 




1 July 2011 < 


Mr. Timothy Jennewine 
Technical Director, Flight Systems 
Engineering Division 
ASC Engineering Directorate 

Mrs. Dawn McGarvey-Buchwalder 
Technical Advisor for Airworthiness, 
oyaieiiia iiiiegicuioii wince 
Former F-35 Pilot Systems Program Lead 
^Former F-22 Life Support Systems Manager 


Broad history of F-22 & 
On-Board Oxygen Generation 
Systems (OBOGS) 


Jun2011- 
Jan2012 


Mr. Anthony Keen 
F-22 Chief Engineer 
Former F-22 Technical Director 




19 July 
2011 


Lt Gen Mark Shackleford, USAF 
SAF/AO Militarv Dermtv 

i VI / 1 V V^/ lVllllLd.1V L 7 LI L y 

Former F-22 System Program Office (SPO) 
Director 


Impacts of acquisition reform; 
Military Specification / Military 

Standard (Mil- Spec/Mil- Std) 
changes; Risk assessment process 


27 July 
2011 


Lt Gen Robert Raggio (USAF ret) 
Former F-22 SPO Director 


Weight reduction Integrated 
Product Team (IPT) process; Mil- 
Spec/Mil-Std changes 


27 July 
2011 


Mrs. Dawn McGarvey-Buchwalder 


Safety Significant/Critical 
process; IPT process; Failure 
Mode Effects Criticality Analysis 
(FMECA) process 


28 July 
2011 


Mr. Larry Carr 
Former Chief, Human Systems Integration 
(HSI) CONOPS, Headquarters USAF 


Evolution of HSI in the Air Force 
&F-22 



137 



8 Aug 2011 


Mr. Jon Ogg 
Former F-22 Chief Engineer 


FMECA; Hazard analysis; Impact 
of erosion of Mil-Spec/Mil-Std; 
ASC & F-22 systems engineering 
capability 


8 Aug 2011 


Mr. Eric Abell 
Former F-22 Chief Engineer 


Weight reduction exercise; F-l 19 
engine robustness; Mil-Spec/Mil- 
Std 


8 Aug 2011 


Mr. Chris Burke 
Former F-22 Chief Engineer 


FMECA; Atrophy of Systems 
Engineering Capability; Safety 
Significant/Critical process; Need 
for development planning 
organizations 


12 Aug 
2011 


Mr. Ronald Dubbs 

Former F-22 Chief Engineer 


Weight reduction exercise; 
Change in responsibility for Mil- 
Spec/Mil-Std; Impact of 

Cnn orp^innpillv mpmrlpitprl Vvurlcrpt 

V^Wllg,! t/OOlVJllClll V lllCU.lVJ.ClLt/VJ. UUVJcit/L 

cuts 


12 Aug 
2011 


Brig Gen William Jabour, USAF (Ret) 
Former F-22 SPO Director 


Mil-Spec/Mil-Std; Weight 
reduction (Key Performance 

PjirjiTTiptpr QJiti ^fnpfinn i fp^tincr 

JT dl CllllC LCI oClLlolClVvLlVJll^ ICoLlllii 


12 Aug 
201 1 


Mr. Douglas Ebersole 
F-35 Director of Engineering 
Former F-22 Chief Engineer 


Environment Control Systems 
testing; Change management 

iji vjVvt/i3o 9 ±>civy vo. u ja.i o y oLt/iiio 

Engineering Processes 


12 Aug 
2011 


Mr. Kevin Burns 
Former F-22 Chief Engineer 


Decision to remove Back-up 

Dyvuph Slv<itpm* Involution nf* 

KJ A. V tiV^ll kJV kMLlll^ \—i V WlUllWll VJ1 

Life Support IPT 


30 Aug 
2011 


Mr. Michael Beauchamp 
Former Director of F-22 Air Vehicle 


Flight testing; F-22 Users Group; 
Lack of OBOGS end-to-end 
testing 


30 Aug 
2011 


Lt Gen CD. Moore, USAF 
Former F-35 Deputy SPO Director 
Former F-22 SPO Director 


Impacts of acquisition reform; 
Navy vs. USAF functional 
capability; Implications of 

capability-based requirements; 
LTSIT imnlpmpntation 

lllJl 1111LJ 1 vlll vll LCI L1U11 


31 Aug 
2011 


Mr. Mark Fraker 
Former F-22 Chief Engineer 


Operational Test & Evaluation; 
Impacts of acquisition reform; 
Independent air worthiness home 
office; HSI progress 



138 



1 Sep 2011 


Lt Gen James Fain, USAF (Ret) 
Former F-22 SPO Director 


Review early days of F-22 
program; Impacts of acquisition 
reform; IPT development 


26 Sep 2011 


Lt Gen Thomas Owen, USAF 
Commander, Aeronautical Systems Center 
Former F-22 SPO Director 


Mil-Spec/Mil-Std; Impact of 
manpower reductions; 
Acquisition Improvement 
Program; Risk assessment and 
evolution of HSI 


26 Sep 2011 


VADM Admiral David Architzel, USN 
Commander, Naval Air Systems Command 

Dr. Allan Somoroff 
Deputy Commander, Naval Air Systems 
Command 


Navy vs. USAF differences in 
implementing Goldwater- 
Nichols; Functional (home office) 
approach to acquisition oversight; 
Mil-Spec/Mil-Std; Inherently 
governmental functions 


10 Oct 2011 


Mrs. Dawn McGarvey-Buchwalder 


IPT; Weight reduction exercise; 
Life Support System Trade Study 


Nov 2011 


Mr. George Miller 

/ii jTLunian r eriorniance wing/ivxii^r 


Several discussions on 
multi-national air quality 
specifications and standards; 
Status of new USAF Air 
Standard Directive 


Jun2011 - 
Dec 2011 


Col Sean Frisbee, USAF 
F-22 SPO Director 


Continual dialogue on program 
history and performance 



Table G-l. Scientific Advisory Board Aircraft Oxygen Generation Study Panel Interviewees. 
Note: The above individuals were interviewed with regard to various general or F-22 
pro gram- specific policies, plans, and procedures that did or might have contributed to 
the various F-22 OBOGS issues or to the Panel's understanding of the background of the 
F-22 program in general and the OBOGS in particular. 



139 



(This Page Intentionally Left Blank) 



140 



Appendix H: 
Study Hypotheses and Questions Examined 



A large number of potential hypotheses and sub-hypotheses were developed by the 
Aircraft Oxygen Generation (AOG) Panel in the course of its study efforts. As they were 
developed and refined, each was analyzed and responses provided by a technical team led by the 
F-22 System Program Office (SPO). As the AOG Study effort evolved and more data was 
received so did the list of hypotheses also evolve. The final hypotheses / sub-hypotheses / 
questions and the originally provided detailed discussion/response for each, as prepared and 
presented by the technical team led by the F-22 SPO, are set forth below. The responses of the 
technical team are provided in blue for clarity. Explanatory comments added after the 
hypotheses were developed and/or the response was presented to the AF Scientific Advisory 
Board (SAB) AOG Panel are provided as needed for clarity and are indicated by brackets [ ]. 

HA Hypothesis Category #1 : 

The F-22 oxygen delivery system is failing to deliver adequate Oxygen 
(0 2 ) to the pilot, resulting in hypoxia symptoms that threaten flight 
safety. 



H.1.1 Hypothesis 1 A: 

The F-22 OBOGS [On-Board Oxygen Generation System] unit can episodically expel the 
contents of the zeolite sieve in such a way that trapped nitrogen, or other gases normally 
resident in ambient air, are passed into the breathing air, thereby reducing delivered 
oxygen to levels that threaten flight safety. 

Response: Testing of OBOGS units at Patuxent River [Naval Air Warfare Center, Patuxent 
River Naval Air Station, Maryland] indicated with pressure transients at the inlet to the 
OBOGS, and particularly when the pressure was reduced rapidly even though it remained 
above the minimum acceptable pressure, could cause CO [Carbon Monoxide] molecules 
normally purged overboard to be expelled into the breathing air. 

Question 1A-1. What are the likely conditions that might cause the F-22 OBOGS to 
episodically expel nitrogen or other gases normally found in ambient air into the breathing air 
that would result in reduced oxygen delivery to the pilot? 

Response: Constituents that will affect O2 content are nitrogen and water. Nitrogen 
would temporarily affect O2 whereas liquid water permanently compromises concentrating 
capability. Pressure transients in OBOGS supply air were suspected of causing an N2 release 
and test results were provided in the SAB brief and are discussed above An aircraft startup 
transient or malfunctioning ECS [Environmental Control System] component could allow liquid 
water into the OBOGS; however, degraded O2 performance and associated weight gain on 
returned OBOGS suggests liquid water has not been an issue on the F-22. 



141 



Question 1A-2. Are there conditions whereby such an event could occur and the 
ICAW [F-22's Integrated Caution, Advisory, and Warning] system not warn the pilot of such an 
occurrence? 

Response: Assuming a properly operating OBOGS O2 sensor and an accurate cockpit 
altitude signal to OBOGS, low O2 due to nitrogen that persists for at least 12 seconds will result 
in an OBOGS FAIL to the pilot due to low PPO2 [Partial Pressure of Oxygen]. A degraded 
OBOGS due to water contamination will similarly result in the same ICAW for the same reason. 
On the other hand, should the OBOGS be in the Auto Mode and the cockpit altitude signal to the 
OBOGS computer fail, the OBOGS could produce a significantly lower PPO2 than desired and 
not illuminate the OBOGS Fail ICAW. 

Question 1A-3. Could these phenomena increase the relative percentages of nitrogen 
and/or reduce the necessary levels of oxygen in the breathing air? 

Response: Yes, although testing has yet failed to replicate an N2 [Nitrogen] expulsion 
coupled with a corresponding reduction in PPO2 that might cause hypoxia. Further, incident 
aircraft OBOGS inspections do not show weight gain nor degraded performance due to liquid 
water contamination. 

Question 1A-4. Should a pilot ingest a greater percentage of nitrogen than desired for 
a given cockpit altitude, could that pilot experience symptoms similar to those associated with 
decompression sickness? 

Response: Although it is possible that a saturation of nitrogen in the blood at altitude 
could cause decompression sickness, aggressive functional testing and the software deep dive of 
the OBOGS system makes such an occurrence highly unlikely. 

H.1.2 Hypothesis 1B: 

A low inlet pressure to the OBOGS unit could result in a lower percentage of oxygen in the 
breathing air, reducing delivered oxygen to levels that threaten flight safety. 

Response: The OBOGS works on the principle of Pressure Swing Adsorption and therefore 
system performance would be degraded by low inlet pressure. This possibility was evaluated 
on flight test aircraft. An ECS shutdown will produce a shutdown of the OBOGS. 

Question 1B-1. What are the conditions that could cause a low inlet pressure to the 
OBOGS unit? 

Response: ECS cutback, ECS shutdown or a Bleed Air Valve Failure will cause the ECS 
to reduce the pressure to the inlet of the OBOGS in such a way that the pilot may not receive the 
required amount of O2. These are known modes and the dash one describes these situations 
along with the appropriate and corresponding actions to be taken by the pilot. Further, certain 
throttle transients could result in lower inlet pressure to the OBOGS. A throttle transient from 
Mil [Military] Power to Idle results in a drop in pressure to approximately 27 psi [pounds per 
square inch] inflight. A review of the flight test data and incident aircraft data shows the input 
pressure to OBOGS drops below the OBOGS regulation pressure only during ECS shutdown 
events. 



142 



Question 1B-2. Could such a condition occur for a period of time long enough to 
affect the quality or quantity of the breathing air and not cause the illumination of an ICAW 
light? 

Response: Referring to the flight test and incident data, the ECS shutdowns are a short 
duration event (approximately 20-25 seconds). Every occasion of an ECS shutdown resulted in 
an ICAW alert to the pilot. In the event of a low inlet pressure to the OBOGS (below OBOGS 
regulation) that results in low OBOGS outlet pressure which drops below 10 psi a "Low 
Pressure" fault is set. 

Question 1B-3. Could such an event also cause a change in the cockpit pressurization? 

Response: Cockpit pressure is unaffected by throttle transients. The cockpit pressure is 
maintained by the cockpit pressure regulator and check valves in the system. If the ECS supply 
pressure is reduced due to an ECS shutdown eventually the cockpit pressure will slowly decay. 
Note: the cockpit pressure vessel is leak tested when the aircraft is delivered and every time a 
canopy is replaced. 

Question 1B-4. Would there be any other indications to the pilot of such a situation? 

Response: The onset of an ECS shutdown is preceded by a "quiet" cockpit. When the 
ECS shutdown occurs , the pilot receives the ECS Fail ICAW. 

H.1.3 Hypothesis 1C: 

The OBOGS, Breathing Regulator Anti-G [BRAG] valve (possibly related to 
Multi-Function Valve interface conditions), or low pressure LSS [Life Support System] 
components downstream of the BRAG Valve may have a failure mode that allows a low 
oxygen condition to exist, reducing delivered oxygen to levels that threaten flight safety. 

Response: A failure of the BRAG valve or the low pressure components between the valve and 
the pilot's mask could result in a failure to deliver adequate O2 under pressure to the pilot. 
The addition of the O2 sensor at the pilot's mask will provide further mitigation of these 
possible failures. 

Question 1C-1. What failure modes could occur that could result in non-OBOGS 
filtered air getting into the breathing air? 

Response: A path between inlet and product gas in the OBOGS, a path between the 
anti-G and breathing air paths in the BRAG valve, or a gross leak or break in lines such that 
system pressures/flows (approximately 2 in H2O [two inches of water pressure] downstream of 
BRAG, and approximately 30 psig [pounds per square inch gauge] between OBOGS and BRAG) 
can't keep up with the leak. Planned system integration testing (January 2012) will quantify how 
much of a leak can cause this issue and if existing aircraft faults and maintenance/pilot checks 
are adequate to find the leak. 

Question 1C-2. What indications would the pilot have to indicate the presence of 
non-OBOGS air in the breathing air? 



143 



Response: Leaks downstream of OBOGS will result in an OBOGS FAIL due to low 
PPO2 because of excessive product flow thru the OBOGS. A leak between the air paths in the 
BRAG valve would not be detectible but will become known to the pilot with the installation of 
the O2 sensor. 

Question 1C-3. Should such a condition occur, under what circumstances would the 
external air have too little oxygen (too high a concentration of other O2 displacing gases) to 
result in hypoxic symptoms? 

Response: At cockpit altitudes above 10,000 feet and depending upon pilot conditioning 
and exertion levels, the pilot could be in an environment whereby the PPO2 might result in onset 
of hypoxia symptoms. 

H.1.4 Hypothesis 1D: 

There may exist a leak or a failure mode in the air delivery path from the Main Engine 
Primary Regulator bleed air valves to the pilot's mask that reduces delivered oxygen to 
levels that threaten flight safety. 

Response: These failures were highlighted in the previous hypothesis. The addition of the O2 
sensor at the pilot's mask will provide further mitigation of these possible failures. 

Question 1D-1. What total system checks are performed on the F-22's air delivery 
path from the Main Engine Primary Regulator bleed air valves to pilot mask valve to determine 
the integrity of the delivery conduit? 

Response: As of April 2011, a Breathing System Integrity Test was added as a 30-day 
recurring inspection. Previously this was done only when replacing a BRAG valve. This test 
verifies there are no leaks in the BRAG valve or the hoses between the BRAG valve and pilot. In 
addition the pilot does a leak test prior to each flight by holding their breath and checking the 
Flow Blinker on the BRAG. If the Flow blinker turns white it is an indication of a leak between 
the BRAG and pilot. Also the "Press-to-Test" button on the BRAG is a rapid inflation of the 
G-suit and test of the positive pressure breathing system. A recurring plumbing leak test was 
added as a 180- day recurring inspection. Previously this test was only accomplished when 
replacing the OBOGS or associated tubing. This test verifies there are no leaks in the lines 
between the OBOGS and BRAG Valve. No recurring inspection occurs for ducting upstream of 
the OBOGS. The ECS system has bleed leak detection upstream from the engine and APU 
[Auxiliary Power Unit] bleed ports up to the primary heat exchanger. This upstream leak 
detection is there primarily to protect structure from damaging bleed air temperatures should a 
leak occur. There is also a leak check conducted once at startup on the warm air manifold. This 
check was added when TMM [Thermal Management Mode] was implemented. The need for the 
check was again to protect structure and other components from APU bleed temperature when 
TMM is activated. There are no additional leak checks of the system downstream. There is 
however monitoring of Avionics Cooling demands and OBOGS outlet pressure that result in 
ICAWs if sufficient pressures are not being provided. Due to the low bleed pressures during 
ground idle operation the system operates just barely above these ICAW limits. Therefore any 
degradation of supply pressure due to a leak should be picked up during ground operation. In 
the case of OBOGS the downstream pressure switch would also indicate if a leak upstream of 
OBOGS was sufficient to degrade OBOGS. 



144 



Question 1D-2. What indicators are available to monitor the performance of the 
delivery conduit? 

Response: The flow blinker is an active monitor of flow in the system which the pilot can 
test at any time to verify there are no leaks. At any time on the ground or inflight, the pilot can 
depress the "TEST" switch on the Breathing Regulator Anti-G (BRAG) valve to provide higher 
pressure oxygen to the mask when the OBOGS is on. Depressing the TEST switch will also 
inflate the lower G-garment and upper pressure vest. 

Question 1D-3. What is the inspection frequency for that conduit? 

Response: See 1D-1 response. [Also] Prior to the SIB [Safety Investigation Board] 
investigation (January 2011), the Breathing System Integrity Test and plumbing leak test were 
only accomplished as a part of regression testing after maintenance that would require the 
removal/replacement of the BRAG valve or other components in the system that could result in a 
system leak. Post January 2011, these inspections were added as periodic. 

Question 1D-4. Is there a failure mode where by a leak could cause a saturation of the 
OBOGS molecular sieve during normal inlet pressure periods and then when low inlet pressure 
occurs, allow inadequate levels of oxygen to be delivered to the pilot? 

Response: Not certain of the potential for this failure mechanism. But if there was a 
downstream leak of the OBOGS coupled with the pilot's breathing that would exceed 200 
liters/minute flow rate it could result in a low PPO2 condition. A One Time Inspection (OTI) that 
performed both the Breathing System Integrity Test and plumbing leak test found approximately 
10% of the [F-22] fleet with either a breathing hose that leaked or a leaking plumbing 
connection. The leaks were large enough to be detected by the testing but not large enough to 
cause an OBOGS FAIL ICAWfor low PPO2. Further testing is planned to evaluate the leak rate 
required to cause dilution at the pilot's mask. 

H.1.5 Hypothesis 1E: 

The F-22 OBOGS unit's scheduled delivery of oxygen to the pilot can be late or impaired in 
its ability to perform satisfactorily based on climb rate, oxygen generation performance or 
a combination of its filter/purge and ambient pressure relationship to the algorithms 
scheduling its operation, reducing delivered oxygen to levels that threaten flight safety. 

Response: While the system is designed to always provide adequate O2 levels based upon 
cabin altitude, system performance could lag aircraft climb performance. CTF [F-22 
Combined Test Force] test data is available that characterizes the delay in O2 concentration 
increases to the pilot. Additionally the added O2 sensor will provide pilot real time status on 
O2 concentration adequacy. 

Question 1E-1. What valves are scheduled by the ambient pressure and desired cockpit 
pressurization schedule that might fail or operate too slowly to ensure proper cockpit 
pressurization or the correct percentage of oxygen to the pilot? 

Response: Three OBOGS charge/vent valves operate to change between 3 charge/vent 
ratios in auto mode to vary O2 concentrating performance as needed for the cockpit altitude. 
The cockpit pressure regulating valve controls proper cockpit pressurization. 



145 



H.1.6 Hypotheses 1 E-1 : 

There may be a combination of conditions in the F-22's operating envelope whereby the 
F-22's Oxygen Delivery System does not deliver the desired percentage of oxygen to both 
the pilot and the breathing vest, which could result in hypoxia and threaten flight safety 
(e.g., sustained period of significant "G'Moading and/or during rapid descents with low 
power). 

Question 1E-1a. Is the ability of the OBOGS to produce oxygen affected by the 
G-loading on the aircraft? 

Response: Flight data does indicate the percentage of O2 production is reduced during 
maneuvers where the aircraft experiences more than 6 Gs. That phenomenon was not observed 
when testing the OGOGS production capability in the centrifuge. Planned system integration 
testing with complete pilot ensemble will investigate/explain O2 concentration G-Dip 
phenomenon. 

Question 1E-1b. When the pilot and breathing vest demand a greater flow of 
breathing air, is the OBOGS unit able to produce the desired percentage of oxygen under all 
conditions? 

Response: In-flight testing of the OBOGS O2 production capability did not indicate a 
significant difference between the O2 produced when using only the mask versus having both the 
mask and the breathing vest connected. Further, the percentage of O2 produced did not vary 
significantly in either of the above situations while using either the MAX [Maximum] or AUTO 
modes. 

Question 1E-1C. If the percentage of oxygen produced is less than desired, but greater 
than the "warning band" schedule, are there potential conditions (e.g., during a period of 
sustained "G-Loading" or physical exertion) whereby a pilot could experience the symptoms of 
hypoxia? 

Response: Oxygen desaturations were not observed during CTF testing in conjunction 
with "G" maneuvering, although O2 concentration G-Dip was observed. Production O2 sensor 
will track OBOGS performance for comparison with Pulse-Ox [Pulse Oximeter] desaturations 
data. 

Question 1E-1d. Are there conditions whereby the breathing rate of the pilot and the 
inflation rate and pressure of the breathing vest could result in short or long term effects to the 
pilot (e.g., Raptor Cough, CNS [Central Nervous System] symptoms, hypoxia)? 

Response: No manned centrifuge testing is currently planned to explore this question 
although the recently formed physiology team is investigating potential causes of Raptor Cough. 

Question 1E-2. What indications does the pilot have to indicate that either the cockpit 
pressure or the percentage of oxygen being delivered is too low? 

Response: Cockpit pressure going outside expected pressure will result in an ICAW to 
the pilot. A low O2 to the pilot will result in an OBOGS FAIL ICAW due to a low PPO2 
condition when 02% [oxygen percentage] falls below the warning band. If cockpit 



146 



pressurization decays below the target set point a cockpit pressure ICAW will set if greater than 
2.5 psi low. Additionally, Update 5 S/W [software] plans to incorporate changes to ensure 
robustness of cockpit altitude signal to OBOGS. Addition of production O2 sensor will provide 
backup indication as to adequacy of O2 concentration. 

H.1.7 Hypothesis 1F: 

There may have been a component in the air delivery path from the APU or Main Engines' 
bleed air sources to the pilot mask valve that has been re-sourced to another vendor in the 
F-22 supply chain, and whose specifications have changed in a way that a different failure 
mode may be able to occur which reduce delivered oxygen to levels that threaten flight 
safety. 

Response: No changes in suppliers or in system specifications were identified that occurred 
after system qualification. A major change in system design occurred during development 
when the Air Force directed the SPO to make use of existing AF [Air Force] Life Support 
equipment rather than to pursue the contractor furnished design and equipment. 

Question 1F-1. Have there been changes in sub-level suppliers since 2007, either a 
new company or in the processes used by the original supplier, to produce parts and/or 
components to the F-22 Oxygen delivery system? 

Response: Yes, although NFF [No Fault(s) Found] on returned LSS components 
(OBOGS and BRAG) plus no pattern on incident hardware serial numbers or manufacture date 
suggests no correlation with these changes and the incidents. 

Question 1F-2. How have their products been tested and/or certified? 
Response: Further investigation is needed to answer this question. 

Question 1F-3. Are any of those components or parts on a critical path with regard to 
safety of flight? 

Response: Further investigation is needed to determine the specific function of the 
changed parts in the OBOGS/BRAG with regards to the safety aspects of the components. 



147 



H.2 Hypothesis Category #2: 

The F-22 oxygen delivery system is either ingesting or allowing a 
leakage of a toxic compound or compounds, which are not being 
filtered from the breathing air and thereby resulting in hypoxia-like 
symptoms that threaten flight safety. 



H.2.1 Hypothesis 2A: 

The F-22 OBOGS unit can become saturated with undesirable agents, thereby reducing its 
effectiveness to filter out Nitrogen or other undesired contaminants (e.g., Argon, CO, 
VOCs [Volatile Organic Compounds], or other toxins), resulting in hypoxic-like symptoms 
that threaten flight safety. 

Response: Saturation of the zeolite crystals with a contaminant could reduce the OBOGS 
performance. This potential was evaluated in laboratory tests which showed this to be unlikely 
without excessive levels of contaminants. 

Question 2A-1. Could the undesired contaminants come from either the bleed air from 
the compressor or from a leak of another substance in any of the heat exchangers? 

Response: Yes. There is a potential that contaminants could be introduced through the 
engine or heat exchangers. But thus far, we have been unable to detect any harmful substance at 
a level that might cause harm to the pilot. 

Question 2A-2. What is the list of undesired contaminants that could be expelled into 
the breathing gas? 

Response: Recommend using the Molecular Characterization Matrix as an attachment 
to address this. 

Question 2A-3. Could the effectiveness of the purge cycle be affected by the 
differential between the OBOGS internal pressure and the external ambient pressure? 

Response: The OBOGS is more efficient at higher altitudes due to the reduced ambient 
pressure. At the lower altitudes, with pressure transients at the OBOGS inlet, testing has shown 
an ability of the OBOGS to expel a greater volume of carbon monoxide into the breathing air. 

Question 2A-4. What are the likely symptoms for a pilot who may have ingested those 
contaminants? 

Response: Symptoms can vary from hypoxic-like to CNS disorders depending on 
contaminant and concentration. Refer to the discussion on the (( Characterization of Chemicals 
on the F-22 " in this report [Page 32 and also Appendix B]. 

Question 2A-5. How did the supplier for the F-22 OBOGS decide the input and output 
filter efficiency and micron size? 

Response: Filter input was selected to protect immobilized zeolite beds from specified 
contamination while maintaining an acceptable pressure drop. Output filters were sized to 



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protect against the potential of failed zeolite bed material propagating downstream into the 
pilots mask. OBOGS Supplier is assessing improved filtration for outlet filter should a change 
be deemed necessary. 

Question 2A-6. With other OBOGS systems using smaller micron size filters, what 
differences in ability to filter undesirable contaminants could be expected? 

Response: Mechanical bed immobilization can allow some zeolite shifting and 
consequential dust generation. Smaller outlet filter size limits introduction of this dust into the 
product gas. 

H.2.2 Hypothesis 2B: 

The F-22 OBOGS unit can episodically expel the contents of the zeolite sieve in such a way 
that trapped undesired contaminants are passed into the breathing air, resulting in 
hypoxic-like symptoms that threaten flight safety. 

Response: A detailed response to characterize the extremely small quantities of VOCs 
released into the product gas under specific test conditions during Honeywell Des Plaines 
OBOGS challenge testing [e.g., testing done at HoneywelVs facility located at Des Plaines, 
Illinois] will be provided as a set of charts. This chart deck will summarize all challenges 
conducted with associated test conditions and results. 

Question 2B-1. What are the likely conditions that might cause the F-22 OBOGS to 
episodically expel undesired contaminants into the breathing air? 

Response: Pressure transients to the OBOGS inlet supply or high humidity at OBOGS 
inlet air supply are suspect conditions based on NAVAIR [Naval Air System Center] and Des 
Plaines Testing. 

Question 2B-2. Are there conditions where by such an event could occur and the 
ICAWS system not warn the pilot of such an occurrence? 

Response: Yes, there are no aircraft warnings for VOCs, CO, or C02 [Carbon 
Dioxide]. 

Question 2B-3. Could this phenomenon produce irritating or debilitating levels of 
undesired contaminants to be ingested by the pilot? 

Response: This question is being addressed by the aviation medical community as part 
of the molecular characterization matrix efforts. Recently formed physiology team is 
investigating potential causes of Raptor Cough. 

H.2.3 Hypothesis 2C: 

The OBOGS, Breathing Regulator Anti-G valve (possibly related to Multi-Function Valve 
interface conditions) or low pressure LSS components downstream of the BRAG Valve 
may have a failure mode that allows a contamination condition to exist, resulting in 
hypoxic-like symptoms that threaten flight safety. 



149 



Response: While none of these components were designed to eliminate potential 
contaminants a leak downstream of the BRAG valve would allow cabin air to enter the system 
which is bleed air from the same source that feeds the OBOGS and assumed to be breathable. 

Question 2C-1. What failure modes could occur that could result in non-OBOGS 
filtered air getting into the breathing air? 

Response: Same answer as 1C-1. 

Question 2C-2. What indications would the pilot have to indicate the presence of 
non-OBOGS air in the breathing air? 

Response: Same answer as 1C-2. 

Question 2C-3. Should such a condition occur, under what circumstances would the 
external air either have too little oxygen or too many other contaminants such that hypoxia 
symptoms would result? 

Response: VOCs introduced at a level that may cause pilot impairment will not 
immediately affect O2 however prolonged VOC exposure has been shown to reduce bed 
concentrating efficiency which does drop O2 concentration (>100 ppm [parts per million] over 
>10 hours reduced O2 output from >90% to 79%). Hypoxia symptoms associated with VOCS 
are being addressed by the aviation medical community as part of the Molecular 
Characterization Matrix efforts. 

H.2.4 Hypothesis 2D: 

There may exist a leak or a failure mode in the air delivery path from the Main Engine or 
APU bleed air sources to the pilot's mask that allows unfiltered contaminants to be 
delivered to the pilot, resulting in hypoxic-like symptoms that threaten flight safety. 

Response: See 1D-1. 

Question 2D-2. What indicators are available to monitor the performance of the 
delivery conduit? 

Response: See 1D-2. 

Question 2D-3. What is the inspection frequency for that conduit? 
Response: See 1D-3. 

Question 2D-4. Is there a failure mode where by a leak could cause a saturation of the 
OBOGS molecular sieve during normal inlet pressure periods and then when low inlet pressure 
occurs, allow unacceptable levels of undesired contaminants to be delivered to the pilot? 

Response: See 1D-4. 
H.2.5 Hypothesis 2E: 

The F-22 OBOGS unit's scheduled delivery of Oxygen to the pilot can be late or impaired 
in its ability to perform satisfactorily based on climb rate, oxygen generation performance 



150 



or a combination of its filter/purge and ambient pressure relationship to the algorithms 
scheduling its operation, resulting in hypoxic-like symptoms that threaten flight safety. 

Response: Addressed in flight test profiles and reported earlier. 

Question 2E-1. What valves are scheduled by the ambient pressure and desired cockpit 
pressurization schedule that might fail or operate too slowly to ensure proper cockpit 
pressurization or the correct filter/purge rate to prevent undesirable contaminants from being 
delivered to the pilot? 

Response: Three OBOGS charge/vent valves operate to change between 3 charge/vent 
ratios in auto mode to vary O2 concentrating performance as needed for the cockpit altitude. 
The cockpit pressure regulating valve controls proper cockpit pressurization but will not affect 
contaminants in the cockpit. 

Question 2E-2. What indications does the pilot have to indicate that either the cockpit 
pressure is too low or the OBOGS is not performing appropriately during the unprecedented 
changes in altitude created by the F-22? 

Response: Same answer as 1E-2. 
H.2.6 Hypothesis 2F: 

There may have been a component in the air delivery path from the Main Engines or APU 
bleed air sources to the pilot mask valve that has been re-sourced to another vendor in the 
F-22 supply chain, and whose specifications have changed in a way that a different failure 
mode may be able to occur which could result in a failure to eliminate an undesired 
contaminant before delivering breathing air to the pilot, resulting in hypoxic-like 
symptoms that threaten flight safety. 

Response: No changes in suppliers or system specifications have been identified. 
Documented hardware failures failed to demonstrate introduction of contaminants into the 
system. 

Question 2F-1. Have there been changes in sub-level suppliers since 2007, either a 
new company or in the processes used by the original supplier to produce parts and/or 
components to the F-22 Oxygen delivery system? 

Response: Same answer as 1F-1, although since this hypothesis is about contaminant 
filtering, the relevant changes would be associated with the OBOGS inlet and outlet filters and 
the zeolite beds and there have been no changes in suppliers for these components. Zeolite beds 
were specifically looked at and the results of investigation were provided to Gen Hoog SIB 
[OBOGS and Aircrew Fight Equipment (F-22 Focus) Class E Safety Investigation Board chaired 
by then-Major General, now Lieutenant General Stephen L. Hoog, USAF]. 

Question 2F-2. How have their products been tested and/or certified? 
Response: Further investigation is needed to answer this question. 



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Question 2F-3. Are any of those components or parts on a critical path with regard to 
safety of flight? 

Response: Performance of these parts is critical to O2 concentrating performance which 
is monitored and substandard performance is alarmed to the pilot via OBOGS FAIL I CAW. 
Although OBOGS does act as a filter for VOCs, the inlet air standards imposed on the Supplier 
do not require it to act as a VOC filter which is why a supplemental aircraft filter is being 
currently investigated. 



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Appendix I: Terms of Reference 



USAF Scientific Advisory Board 
Quicklook Study 
Aircraft Oxygen Generation 

Background 

Many aircraft make use of an on-board oxygen generation system to provide breathing oxygen 
for the aircrew. Recently, there have been a number of hypoxic-related incidents that may be 
related to OBOGS or its installation. An investigation of system safety issues involving OBOGS 
is required to ensure that the appropriate steps are being taken to enhance flight safety of these 
aircraft. 

Charter 

The Study will: 

• Continue the evaluation of the F-22 oxygen (O2) system to include developing the means to 
gather dynamic in-flight information to identify the root cause of reported hypoxia incidents. 

o Recommend refined peacetime altitude restrictions when greater data fidelity is available 
on OBOGS overall fleet wide performance. 

o Review current aircraft O2 design and offer any changes, if required, for the F-22 
configuration of OBOGS, BRAG valve, back-up O2 supplies, automatic system 
activation, PVI design, and overall system inspection/self-test cycle. 

• Evaluate OBOGS, and life support systems in general, to determine commonalities and 
acquisition philosophy across MDS and identify design limitations and/or key assumptions. 

o Review practice of "fly to warn" systems that may only allow the absolute minimum 
level of 2 required in rapid decompression situations. 

o Make recommendations on the use of "automatic activation" backup O2 with respect to 
normal aircraft operating altitude and agreed-upon aviator response time. 

• Evaluate further investigation into contaminants that potentially impact OBOGS operation 
and follow-on performance effects on aircrew. 

o Ensure testing includes dynamic ECS-induced temperature heat/cooling cycle that may 
affect the chemical composition of various aircraft inlet-ingested contaminants. 

o Explore the development and fielding of filters or catalysts to negate the impact of the 
most likely contaminants found in OBOGS product gas when operating in common 
aviation environments (combat and peacetime). 

• Direct and evaluate, if able, human response to high altitude, rapid cabin altitude changes, 
and rapid decompression environment with less than 90% supplied O2. 

o If warranted, based on F-22 oxygen sensor data, direct evaluation of low O2 (less than 
21%) at altitude for sustained and transient exposure. 



153 



o Fully explore the impact on OBOGS standard (max) 93% O2 content on decompression 
sickness/pre-breathing requirements. 

• Revalidate and make recommendations to clarify guidance for Air Standards with specific 
guidance on effect of systems deigned to minimum acceptable standards. 

• Review and validate the implementation of performance based contract acquisition programs 
and risk analysis protocols. 

• Examine those incidents that are occurring in flight regimes which are normally considered 
unlikely for a hypoxic event (e.g., 8,000 ft cabin altitude pressures). 

• Review and validate all associated aircrew flight equipment affiliated with OBOGS-equipped 
aircraft. 

• Priority should be given to the F-22 aircraft but expanding the scope to include the F-16, 
A- 10, F-15E, B-l, B-2, CV-22, T-6, F-35, F-18 and other aircraft is authorized if appropriate. 

Study Products 

Written, public-releasable report presented to the SAF/OS upon completion. A preliminary 
report provided to the SAF/OS by June 30, 2011 with follow-on reports provided every 60 days 
until completion. Planned completion in November 201 1 . 



154 



Appendix J: Study Members 



Study Leadership 

Study Chair: General Gregory S. Martin, USAF (Ret) 

Study Vice Chair: Lieutenant General George K. Muellner, USAF (Ret) 

Members and Consultants 

Major General Joseph T. Anderson, USMC (Ret) 
Mr. James W. Brinkley 
Honorable Dr. Lawrence J. Delaney 
Dr. Peter F. Demitry, MD, MPH 
Dr. David H. Moore 

General Thomas S. Moorman, USAF (Ret) 

General Officer / Senior Executive Service Participants 

Major General Noel T. Jones, USAF, AF/A5R 

Major General Robin Rand, USAF 

Dr. Thomas P. Ehrhard, SES, AF/CC-SA 

Government Participant 

Colonel Eric A. Kivi, USAF, AFSC/SEF 

Study Support 

Lieutenant Colonel Edward J. Ryan, USAFR 
Lieutenant Colonel Norman F. Shelton, USAF 
Lieutenant Colonel Matthew E. Zuber, USAF 
Major Christopher D. Forrest, USAF 
Major Ryan W. Maresh, USAF 
Major Brian T. Stahl, USAF 
Captain Andrew Anderson, USAF 
Mr. William M. Quinn 



155 



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156 



Appendix K: Study Meetings and Briefings 



Overviews/Perspectives 

Air Force Leadership: 
Honorable Michael Donnelly 
General Norman Schwartz, USAF 

Former/Current F-22 Chief Engineers: 

Mr. Eric Abell 

Mr. Mark Fraker 

Mr. Tim Keen 

Mr. Bruce Peet 

Mr. Jon Ogg 

Former/Current F-22 Program Managers 

Air Force Scientific Advisory Board 

Lt Gen James A. Fain, USAF (Ret) 

Lt Gen Thomas J. Owen, USAF 

Lt Gen Robert F. Raggio, USAF (Ret) 

Lt Gen C. D. Moore II, USAF 

Brig Gen William J. Jabour, USAF (Ret) 

Col Sean M. Frisbee, USAF 

Commander, Aeronautical Systems Center 
Lt Gen Tomas J. Owen, USAF 

Commander, Naval Air Systems Command 
Vice Admiral David Architzel, USN 

HQ Air Force 

SAF/AQR/AQX 

AF/A3/5 

AF/A4/7 

AF/A9 

AF/JA 

AF/SG 

AF/ST 

USAF Major Commands 

Air Combat Command 
ACC/A3/A4/SG 
9 th AF/SE 

1 st FW/l st MXG/AFETS 
Air Education and Training Command 
AETC/A3/SG 
59 th MDTS 
43 rd FS 



Air Force Materiel Command 
AFMC/SG/SE 

AFFTC/412 th TW/F-22 CTF/95 th AMDS 
46 th Test Wing 

71 1 th Human Performance Wing 
ASC/F-22 SPO/EN/WI/WW/WN 
AF Research Laboratory 
USAF School of Aerospace Medicine 

Other Air Force 

AF Human Systems Integration Office 

AF Institute of Technology 

AF Safety Center 

3 rd FW/3 rd AOG/3 rd AMXS 

302 nd FS (USAFR) 

Other DoD 

F-35 Joint Program Office 
OUSD (AT&L)/F-35 
Naval Air Warfare Center 
Naval Air Systems Command 

Industry 

Boeing 

Cobham Mission Systems 

Columbia Analytical Services 

Honeywell 

Lockheed Martin 

Mayo Clinic 

Pratt & Whitney 

Wyle Corporation 

Other Government/FFRDCs/Universities 

Edgewood Chemical Biological Center 
Lawrence Livermore National Laboratories 
NASA Dryden Flight Research Center 
NASA Houston Johnson Space Center 
Sandia National Laboratories 
University of Colorado 
University of Tennessee 



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158 



Appendix L: Glossary 



The terms and associated definitions used herein were derived from various sources and 
reflect the collective judgment of the Air Force Scientific Advisory Board Aircraft Oxygen 
Generation Study Panel as what would appropriately reflect the intended meaning of the term 
within the context of this Study Final Report. 

13X Zeolite - A type of synthetic zeolite used in On-Board Oxygen Generation Systems 
(OBOGS) systems. 13X Zeolite was first synthesized in 1950 and is readily available for 
use in commercial molecular sieves. See entries for Molecular Sieve and Zeolite. 

A-10 Thunderbolt II - A United States Air Force (USAF) twin jet attack aircraft developed by 
Fairchild-Republic Company in the 1970s. Its primary mission is to provide close air 
support. The A-10 has a large amount of armor to protect the pilot and vital aircraft 
systems and was designed around a large 30 millimeter automatic cannon which forms 
the primary armament of the aircraft. A- 10s have been upgraded with new avionics and 
many are also receiving a new wing. The USAF currently flies over 300 A-10 aircraft. 
The latest version, the A- 10C, is being upgraded with an OBOGS to replace the previous 
liquid oxygen (LOX)-based system. 

Acquisition Lightning Bolts - A series of nine acquisition improvement initiatives started in 
1995 by the Assistant Secretary of the Air Force (Acquisition) to support the DoD's 
acquisition reform efforts. They were intended to streamline and improve acquisition and 
sustainment practices. 

Acquisition Improvement Plan - An internal USAF effort to improve the capabilities and 
outcomes of its acquisition system. The plan has five main goals: (1) revitalize the 
acquisition workforce, (2) improve the requirements generation process, (3) instill budget 
and financial discipline, (4) improve Air Force major systems source selections, and (5) 
establish clear lines of authority and accountability within acquisition. 

Acute Exposure - A single exposure to a substance (normally not lasting more than a day) that 
can result in severe biological harm or death (although the exposure may have no harmful 
result in a given instance). The Environment Protection Agency has established Acute 
Exposure Guideline Levels defining threshold exposure limits for the general public and 
that are applicable to emergency exposure periods ranging from 10 minutes to 8 hours. 

Advanced Medium-Range Air-to-Air Missile (AMRAAM) Vertical Eject Launcher (AVEL) 
.Replacement instrumentation Package (ARIP) - ARIP is a pod carried on F-22 test 
aircraft that contains a variety of data recorders, processors, power supplies, transponder, 
and data telemetry equipment. The system forms the core of the F-22 test enterprise's 
capability to record and transmit flight test data. 

Advanced Tactical Fighter (ATF) - The ATF program began in 1981 and was the precursor 
name for the acquisition program that eventually developed and produced the F-22 
Raptor. It was a demonstration and validation program undertaken by the United States 



159 



Air Force to develop a next-generation air superiority fighter to counter emerging 
worldwide threats. Lockheed and Northrop were selected in 1986 to develop the YF-22 
and the YF-23 demonstrator aircraft, respectively. These aircraft were evaluated in 1991 
and the Lockheed YF-22 was selected and later developed into the F-22 Raptor. 

Air and Space Interoperability Council - The Air and Space Interoperability Council (ASIC) 
is a formal five nation military organization with a mandate to enhance coalition 
warfighting capability through air and space interoperability. Member nations are those 
within the Five Eyes (United States, United Kingdom, Australia, New Zealand, and 
Canada) community and consist of representation from their respective Air Forces, and 
also includes the United States Navy. The ASIC was originally called the Air 
Standardization Coordination Committee. See entry for the Air Standardization 
Coordination Committee. 

Air Cycle Machine - The refrigeration unit of the environmental control system used in 
pressurized gas turbine-powered aircraft. The air cycle cooling process uses air instead 
of a phase changing material such as Freon in the gas cycle meaning that no condensation 
or evaporation of a refrigerant is involved, and the cooled air output from the process is 
used directly for cabin ventilation or for cooling electronic equipment Normally hot 
compressed turbine engine bleed air is directed into a primary heat exchanger. Outside 
air at ambient temperature and pressure is used as the coolant in this air-to-air heat 
exchanger. Once the hot air has been cooled, it is then compressed. This compression 
heats the air and it is sent to the secondary heat exchanger, which again uses outside air 
as the coolant. See entry for Environmental Control System. 

Air Force Specialty Code - An alphanumeric code used by the United States Air Force to 
identify an Air Force Specialty (AFS) applicable to officers or enlisted personnel. The 
AFSC is similar to the Military Occupational Specialty (MOS) used by the United States 
Army or Ratings used by the United States Navy. AFSC is sometimes used as shorthand 
for "required specific skill sets" or "job description" or "position description." 

Air Standard - A military aviation-related standard produced and distributed by the Air 
Standard Coordinating Committee now called the Air and Space Interoperability Council. 
See the entries for Air and Space Interoperability Council and Air Standard Coordinating 
Committee. 

Air Standard Coordinating Committee (ASCC) - An organization formed in 1948 to manage 
the Air Standardization agreement between Canada, the United Kingdom, and the United 
States. The Agreement was intended to enable them to conduct combined air operations 
and provide each other with certain essential services. Also the ASCC promoted the 
economies that would result from standardizing air materiel support and encouraged the 
exchange of research and development information. The ASCC was expanded to include 
Australia in 1964 and New Zealand in 1965. See entry for Air and Space Interoperability 
Council. 

Aldehydes - A class of organic compounds that contain the carbonyl group, and in which the 
carbonyl group is bonded to at least one hydrogen. Aldehydes are formed by partial 
oxidation of primary alcohols and form carboxylic acids when they are further oxidized. 
Aldehydes are used for the manufacture of synthetic resins (e.g., Bakelite), and for 



160 



making dyestuffs, flavorings, perfumes, and other chemicals. Some are used as 
preservatives and disinfectants. 

Alkanes - A class of organic substances (also known as paraffins or saturated hydrocarbons) are 
chemical compounds that consist only of hydrogen and carbon atoms and are bonded 
exclusively by single bonds (i.e., they are saturated compounds). The simplest alkane is 
methane. Saturated oils and waxes are examples of larger alkanes. Alkanes are not very 
reactive and have little biological activity. 

Alkenes - An unsaturated chemical compound containing at least one carbon-to-carbon double 
bond. The simplest alkene is ethylene. 

Alkynes - Hydrocarbons that have a triple bond between two carbon atoms. One example of an 
alkyne is acetylene. 

Alveolar Gas Equation - The partial pressure of oxygen in the pulmonary alveoli (Pa02) of the 
human lung is required to calculate both the alveolar-arterial gradient of oxygen and the 
amount of right-to-left cardiac shunt, which are both important in determining 
susceptibility to and evidence of hypoxia. However it is not practical to take a sample of 
gas from the alveoli in order to directly measure the partial pressure of oxygen. The 
alveolar gas equation was first characterized in 1946 and allows the calculation of the 
alveolar partial pressure of oxygen from data that is practically measurable. The alveolar 
gas equation is: 

P A 2 = ( F.02 * (Patmos " P H 2o)) " (P a C0 2 / RQ) 

where FiC^ is the fraction of inspired oxygen, P a tmos is the ambient atmospheric pressure, 
and P H 2o is the water vapor pressure at 37°C. The respiratory quotient (RQ) is the ratio 
of CO2 eliminated divided by the O2 consumed. 

Argon - A chemical element that is found in gaseous form within the Earth's atmosphere and is 
the third most common gas in the atmosphere (about 1 percent). Argon is considered an 
inert gas at normal atmospheric pressure, as it is stable and resistant to bonding with other 
elements. OBOGS systems concentrate Argon as a byproduct of their oxygen 
concentration processes. In the F-22 the OBOGS product air can be almost 6 percent 
Argon by volume when the system is producing its maximum concentration of Oxygen. 

Automatic Ground Collision Avoidance System (AGCAS) - AGCAS is a software 
application that keeps track of the aircraft's position, speed, and altitude against a digital 
terrain map of the Earth. The system intervenes if the pilot becomes disoriented, or 
suffers a G-induced loss of consciousness. A pilot warning is issued a specified period of 
time (a few seconds) before the flight computer takes control of the aircraft. If the pilot 
fails to react to the warning the auto-GCAS system takes control of the aircraft. In 
general the AGCAS will immediately roll the aircraft to a wings-level orientation and 
initiates a vigorous pull-up maneuver. The computer gives control back to the pilot after 
it restores the aircraft's stability. An AGCAS is set to be implemented on certain F-16 
blocks, the F-22, and the F-35. 

Auxiliary Power Unit (APU) - A device on an aircraft that provides electrical power or 
compressed air (or both) for functions other than propulsion. They are commonly found 
on larger aircraft, but can also be installed on fighter-type aircraft as well. APUs usually 
help free an aircraft from reliance on ground power units for engine start and other 



161 



purposes and can provide "housekeeping power" for the environmental control system, 
electrical, and hydraulic systems when the main propulsion system(s) are not operating. 

AV-8B - The Boeing AV-8B Harrier II is a single-seat, single engine second-generation 
vertical/short takeoff and landing ground- attack aircraft flown by the United States 
Marine Corps. It utilizes an OBOGS system to provide breathing oxygen to the pilot. 

Aviation Breathing Air Standard - A not-yet produced but recommended Air Standard to be 
developed by the United States Air Force Research Laboratory and put forward to the 
five-nation Air Standard Coordinating Committee (ASCC) See entry for the ASCC. 

Aviation Physiology - Aviation physiology is the medical/scientific discipline that deals with 
the physiological challenges encountered by pilots and passengers when subjected to the 
environment and stresses of flight, especially high-human stress aviation activities such 
as military tactical flight operations (high altitude, rapid pressure changes, high 
g-loading, etc.). 

B-1B - The Boeing B-1B Lancer is a variable- sweep wing bomber used by the United States Air 
Force (USAF). It has four turbofan engines and employs a blended wing-body design to 
achieve a maximum speed of about Mach 1 .25 and is optimized for low level penetration. 
The B-1B has a normal aircrew of four and is currently used only in a non-nuclear role. 
The B-1B generates its own breathing oxygen for crew use via an OBOGS-type system. 

B-2A Spirit - The B-2A is a multi-role bomber flown by the USAF. It is capable of delivering 
both conventional and nuclear munitions. Its low-observable, or "stealth," characteristics 
give it the ability to penetrate sophisticated defenses and threaten heavily defended 
targets. The B-2's low observability is derived from a combination of reduced infrared, 
acoustic, electromagnetic, visual, and radar signatures. The B-2 utilized and OBOGS 
system to provide breathing oxygen to the aircrew. 

Backup Oxygen System (BOS) - A BOS provides oxygen to the aircrew (and if applicable, 
passengers) in the absence or failure of the primary life support system(s) that normally 
provides breathing air. A BOS may use gaseous or liquid oxygen, depending on design, 
and its operating duration is generally in the 10-60 minute range. The BOS can be 
recharged on the ground via a maintenance action or (in some systems) in the air by the 
primary system once full operational function is restored (in-air restoration applies 
mainly to OBOGS type primary systems). In a fighter-type aircraft a BOS may be 
aircraft or ejection seat-mounted. 

Bleed Air - Compressed air extracted from the compressor section (i.e., prior to fuel injection 
and combustion) of a gas turbine engine. Bleed air is usually at a relatively high pressure 
and temperature and can be used for deicing, cabin pressurization, etc. For many uses 
(cabin air, environmental control system, avionics cooling, etc.) the bleed air must first be 
cooled by the environmental control system. See the entry for Environmental Control 
System. 

Bottom Up Review - In 1993 Secretary of Defense initiated a comprehensive review of the 
nation's defense strategy, force structure, modernization, infrastructure, and foundations. 
The results of this "Bottom Up Review" provided a basis for a reassessment of defense 
concepts, plans, and programs and was used as the basis/rationale for a large number of 
significant DoD program, budget, and resource changes and reductions. 



162 



Breathing Regulator Anti-G (BRAG) Valve - In the F-22, the pilot is equipped with an 
integrated, fast acting BRAG valve that controls the flow of air to the mask, the 
counter-pressure vest, and the G-suit, the latter acting as a partial pressure suit at high 
altitude. 

Broad Area Review (BAR) - A group of highly qualified individuals with a broad background 
of experience in the issues/programs to be reviewed and analyzed. Normally the 
members are all government (military and civilian) personnel although sometimes outside 
industry or other experts are asked to serve as advisors. This is in contrast to a review by 
a group chartered under the Federal Advisory Committee Act (such as the Defense 
Science Board or the AF Scientific Advisory Board) where none of the members may be 
government employees (although a few government personnel are sometimes asked to 
serve as advisors). Also a BAR and its members, given that they are government 
employees, are not necessarily considered to be offering independent advice to their 
government sponsor (which does not inhibit most BARs, in practice, from being quite 
objective). 

Built In Test (BIT) - A mechanism that permits a machine (mechanical or electronic) to test 
itself. BIT is commonplace in weapons, avionics, medical devices, automotive 
electronics, complex machinery of all types, unattended machinery of all types, and 
integrated circuits. 

C2A1 Filter - A system designed to filter breathing air, originally certified for use in a 
chemically contaminated warfare environment. The filter has been tested against military 
and National Institute for Occupational Safety and Health protocols, and found to be 
effective against a number of different chemical warfare and industrial chemicals. It was 
temporarily incorporated into the F-22 pilot life support system to filter potential 
contaminants, with the filter (a high efficiency particulate filter material combined with 
activated carbon and charcoal for chemical absorption) being replaced after each flight. 
The filter is no longer being used routinely in the F-22. 

Cabin/Cockpit Pressure - A measure (usually expressed in feet of altitude, e.g., "a cabin 
altitude of 5,000 feet") of the atmospheric pressure being maintained in the aircrew 
compartment by an aircraft's environmental control system. Most current commercial 
aircraft can maintain an internal (cabin) altitude/pressurization of about 8,000 feet up to 
an actual aircraft altitude of 40,000 feet. In general, if the cabin altitude cannot be 
maintained below a set level (often 10,000 feet) supplemental oxygen is usually required. 
Tactical aircraft usually operate at a higher cockpit altitude to reduce the deleterious 
airframe and aircrew effects of a rapid or explosive decompression due to battle damage. 
The F-22 operates with a cabin altitude between sea level and no higher than 25,000 feet 
depending on the actual altitude at which it is flying. Normally the life support system 
provides the pilot, through his oxygen mask, whatever supplemental oxygen is required. 

Carbon Dioxide (CO2) - A naturally occurring chemical compound composed of two oxygen 
atoms covalently bonded to a single carbon atom. CO2 is a gas at standard temperature 
and pressure and exists in Earth's atmosphere in this state, as a trace gas at a 
concentration of 0.039% by volume. Plants absorb carbon dioxide and produce oxygen. 
Carbon dioxide is also produced by combustion of coal or hydrocarbons (such as occurs 
in jet engines). CO2 is an asphyxiant gas and not classified as toxic or harmful in low 



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concentrations. Concentrations of 7% to 10% may cause suffocation, manifesting as 
dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few 
minutes to an hour. 

Carbon Monoxide, Carbon Monoxide Poisoning - Carbon monoxide (CO) is a product of 
incomplete combustion of organic matter due to insufficient oxygen supply to enable the 
complete oxidation of CO2. CO is a colorless, odorless, and tasteless gas and therefore 
difficult for a human to detect. Carbon monoxide mainly causes adverse effects by 
combining with hemoglobin to form carboxyhemoglobin in the blood. This prevents 
oxygen binding to hemoglobin, reducing the oxygen-carrying capacity of the blood, 
leading to hypoxia. Symptoms of mild acute poisoning can include lightheadedness, 
confusion, headaches, vertigo, and flu-like symptoms. Higher exposures can lead to 
significant toxicity and even death. 

Carboxyhemoglobin Level - Carboxyhemoglobin is hemoglobin combined with carbon 
monoxide. The carboxyhemoglobin level is a measure of the amount of carbon 
monoxide which has been absorbed into the blood stream. Because carbon monoxide has 
a much greater affinity to bind to hemoglobin than oxygen, even small amounts of carbon 
monoxide will significantly reduce the blood's ability to transport needed oxygen within 
the body. 

Central Nervous System (CNS) - The CNS consists of the brain and the spinal cord and 
contains the majority of the neurons in the body. 

Combat Edge - A set of specially designed pilot-worn life support equipment designed to 
improve tolerance to high-G maneuvers and help prevent G-induced loss of 
consciousness. The system is intended to provide pilots greater endurance during 
high-performance maneuvers up to +9 Gs. 

Combined Test Force - A test organization in which all test stakeholders (contractor, 
government operational and development testers, and government users) are represented. 
Test assets and test infrastructure are shared. This reduces the infrastructure and test 
asset needs compared to the situation that would exist if each stakeholder had to purchase 
and operate its own infrastructure and test assets. Test planning is done cooperatively 
and test missions may collect data for multiple stakeholders on the same mission. 
Although planning and conduct of test missions are cooperative, and data is shared; data 
analysis, evaluation, and test reporting are usually independent activities conducted by 
each stakeholder to support their own objectives and interests. 

Commercial Off the Shelf (COTS) - Software or hardware, technology, or other products that 
are ready-made and available for sale, lease, or license to the general public. COTS items 
require no unique government modifications or maintenance over the life cycle of the 
product to meet the needs of the procuring agency. Motivations for using COTS 
components include reduction of overall system development and costs. There are 
sometimes maintenance cost advantages to using COTS equipment, but since the 
lifecycle of COTS systems are determined by public desire, they can be subject to 
availability issues after some period of time. 

CPK Equation - The Coburn-Forster-Kane (CPK) equation is the most sophisticated approach 
currently available to model carbon monoxide uptake by humans and animals. 



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CRU-93 - A diluter-demand, g-compensated oxygen regulator that provides automatic pressure 
breathing as a function of both altitude and G-forces. The pressure breathing for G 
function is activated by a pressure signal from an external anti-G valve and is used with 
an USAF counter-pressure vest and high pressure mask/helmet assembly to form the 
"COMBAT EDGE" ensemble. This regulator is currently being used on the 
F-16A/B/C/D. 

CRU-94 - An integral component of the Combat Edge System is the CRU-94/P. Providing 
pressure breathing for G capability to tactical aircrew, it reduces the probability of 
G-induced loss of consciousness during high performance flight. It is specifically 
designed to distribute pressurized breathing gas from the aircraft-mounted regulator to 
the pilot's oxygen mask and bladders, located in the vest and lightweight HGU-55/P 
helmet, which is specially configured for Combat Edge. 

CRU-98 - In addition to pressure breathing as a function of altitude and air dilution features, this 
regulator incorporates pressure breathing as a function of G (PBG). With this added 
feature the regulator receives a pressure input signal from a remotely located G- valve to 
provide the appropriate PBG outlet pressure. This regulator is used on the F-15 MSOGS 
and F- 1 6 OBOGS aircraft. 

CRU-120 - This personal connector combines the features of the CRU-94/P Integrated Terminal 
Block with the CRU-79 Oxygen Regulator. It allows the Combat Edge ensemble to 
interface with a regulated emergency oxygen system. Operation of the CRU-79 oxygen 
regulator significantly improves pilot breathing comfort during emergency conditions 
while extending the emergency oxygen duration. It is currently installed on the US Air 
Force F-16. 

CRU-122 - The CRU-122 allows the Combat Edge ensemble to interface with a regulated 
emergency system and provides an important role in oxygen backup. It supplies oxygen 
at a slight positive pressure, preventing inward leakage and improving pilot breathing 
comfort during emergency conditions. This personal connector extends the emergency 
oxygen duration while automatically increasing positive pressure above 40,000 feet. The 
CRU-122 is currently installed on the F-22. 

Defense Acquisition Board - The DAB is the DoD's senior-level forum for advising the Under 
Secretary of Defense for Acquisition, Technology, and Logistics on critical decisions 
concerning major defense acquisition programs. The DAB is composed of the DoD's 
senior executives including the Service Secretaries and the Vice Chief of the Joint Chiefs 
of Staff. 

Data Transfer Cartridge (DTC) - The F-22's DTC is located in the cockpit and used to upload 
and download operational, maintenance, and other data. With regard to maintenance of 
the F-22, during a mission various faults in the aircraft systems are noted and recorded by 
its on-board maintenance systems for later analysis and diagnostic activities. This fault 
data is transferred to and archived in the DTC during the mission. When a pilot returns 
from a mission, the DTC is removed and brought to the maintenance activity. If any 
failures occurred on the mission, those fault codes have been noted in the DTC and that 
data is downloaded into the maintenance support cluster computer so the cause of the 
failure can be identified. 



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Demonstration/Validation (DemVal) - A term used in a previous version of the Defense 
Acquisition System (circa 1990) that was the second phase in the acquisition life cycle. It 
consisted of the steps necessary to resolve or minimize logistics problems identified 
during Concept Exploration and Definition, verify preliminary Design and Engineering, 
build prototypes, accomplish necessary planning, and fully analyze trade off proposals. 
The objective of DEMVAL was to validate the choice of alternatives and to provide the 
basis for determining when to proceed into Engineering and Manufacturing 
Development. 

Desorption Tube - A means for trapping (absorbing) potential volatile organic compounds over 
a given sampling period. Once the samples are collected the tubes are capped and taken 
to an analysis facility and heated. The non-reactive, inert absorbent matrix inside the 
tube then "desorbs" the compounds (if any) allowing them to be measured and analyzed. 
Desorption tubes were used extensively in F-22 OBOGS testing at Edwards AFB and 
other locations. 

Dienes - In organic chemistry a diene is a hydrocarbon that contains two carbon double bonds. 
Dienes occur occasionally in nature but are widely used in the polymer industry. 

DoD Acquisition Milestones (A, B, and C // I, II, and III) - The management framework for 
defense systems acquisition is commonly referred to as the acquisition life cycle. The 
acquisition life cycle of the F-22 was sufficiently lengthy that is was developed under two 
different DoD acquisition milestone systems. The current DoD life cycle process 
consists of phases separated by decision points called milestones. Milestones (MS) 
established by Department of Defense Instruction 5000.02 are: 

• MS A approves entry into the Technology Development phase, 

• MS B approves entry into the Engineering and Manufacturing Development phase 
(Note: formal program initiation normally occurs at MS B), and 

• MS C (formerly MS III) approves entry into the Production and Deployment phase. 
The above contrasts with the previous DoD acquisition system: 

• Milestone approves entry into the Concept Exploration phase, 

• Milestone I approves entry into the Program Definition and Risk Reduction phase, 

• Milestone II approves entry into the Engineering and Manufacturing Development 
phase, and 

• Milestone III approves entry into the Production, Fielding, and Support phase. 

Emergency Oxygen System (EOS) - An EOS provides oxygen to the aircrew (and if 
applicable, passengers) in the absence or failure of the primary life support system that 
normally provides breathing air and after failure of the back-up oxygen system if so 
equipped. An EOS normally is designed to use gaseous oxygen and its operating 
duration is generally in the 10-15 minute range. The EOS can be recharged on the 
ground via a maintenance action. In a fighter-type aircraft an EOS is generally ejection 
seat-mounted as it also provides breathing air to the pilot during and after ejection. See 
Backup Oxygen System entry. 



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Engineering and Manufacturing Development (EMD) Phase - In DoD acquisition, EMD 
begins at Milestone B, which is normally formal program initiation. This phase is 
intended to complete the development of a system or increment of capability complete 
full system integration, develop an affordable and executable set of manufacturing 
processes, complete system fabrication, and start test and evaluation. In EMD, the 
program, the system architecture, and system elements down to the configuration item 
(hardware and software) level are defined, system design requirements are allocated 
down to the major subsystem level and are refined as a result of developmental and 
operational tests and iterative systems engineering analyses. The support concept and 
strategy are refined with detailed design-to requirements determined for the product 
support package elements. 

Environmental Control System - The Environmental Control System (ECS) of an aircraft 
provides air supply, thermal control, and cabin pressurization for the crew and 
passengers. Avionics cooling, smoke detection, and fire suppression are often considered 
part of an aircraft's ECS. On most turbine-powered aircraft, air is supplied to the ECS by 
being "bled" from a compressor stage of the gas turbine engine, upstream of the 
combustor. The temperature and pressure of this "bleed air" varies widely depending 
upon which compressor stage is being utilized and the power setting of the engine. 

Specific to the F-22 ECS: 

The F-22 uses an integrated ECS that provides thermal conditioning throughout the flight 
envelope for the pilot and the avionics. The ECS accomplishes avionics cooling, 
provision of air to the pilot; canopy defogging, cockpit pressurization; and fire protection. 

The air cycle system takes engine bleed air (which is between l,200-to-2,000 degrees 
Fahrenheit) and cools it to approximately 400 degrees via a heat exchanger. From there 
the air goes into an air cycle refrigeration machine (which also removes any water) and 
comes out at about 50 degrees. This cooled air is also fed into the OBOGS to provide 
breathable oxygen to the pilot, to operate the Breathing Regulator/Anti-G valve, to 
provide canopy defogging, and to provide cockpit pressurization. 

A liquid cooling system is also a part of the overall F-22 ECS. Polyalphaolefin (PAO) is 
the medium used in the liquid cooling system. One loop cools the mission critical 
avionics and keeps them at about 68 degrees F. The PAO passes through a vapor cooling 
system and a filter and is routed to the F-22 avionics and then out to the wings to cool the 
embedded sensors before entering the second cooling loop. The PAO then is routed to 
the fuel tanks, where the heat is transferred to the fuel (used as a heat sink). 

The now-warm fuel is circulated through an air-cooled heat exchanger (which utilizes 
cool/cold air taken from the boundary layer diverter between the inlet and the F-22's 
forward fuselage) to cool the fuel. Another loop is used to cool the engine lubricants. 

Epidemiological - Relating to epidemiology, the branch of medicine that deals with the study of 
the causes, distribution, and control of disease or other medical conditions in human 
populations. 

Esters - A common type of chemical compound formed by condensing an acid with an alcohol. 
Esters are widespread in nature and are widely used in industry and are encountered daily 
by most people. For example, most naturally occurring fats and oils are the fatty acid 



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esters of glycerol. Esters with low molecular weight are commonly used as fragrances 
and found in essential oils. Phosphoesters form the backbone of DNA molecules. Nitrate 
esters, such as nitroglycerin, are known for their explosive properties, while polyesters 
are important plastics. 

F-15C/D/E - The F-15 Eagle is an all-weather tactical fighter designed to gain and maintain air 
superiority in aerial combat. The F-15C Eagle is an updated version of the F-15 A. It 
entered the Air Force inventory beginning in 1979 and has many improvements including 
additional internal fuel, provision for carrying exterior conformal fuel tanks and increased 
maximum takeoff weight. Additional enhancements include an upgraded central 
computer; ability to employ advanced versions of various air-to-air missiles; an expanded 
electronic warfare system, and radar improvements. The F-15E is a two-crew version 
optimized for air-to-ground attack. The F-15E utilizes an OBOGS-type system. 

F-16C/D (Block 40, Block 50) - The F-16 Fighting Falcon is a multi-role tactical fighter aircraft 
flown by the USAF and numerous other Air Forces around the world. The F-16 Block 40 
series is the improved all-day/all- weather strike variant equipped with LANTIRN pod 
and features strengthened and lengthened undercarriage, an improved radar, and a Global 
Positioning System (GPS) receiver. Block 50 F-16s are have an improved GPS/Inertial 
Navigation System, and the ability to carry additional advanced munitions such as the 
AGM-88 High speed Anti-Radiation Missile, Joint Direct Attack Munition, Joint Stand 
Off Weapon, and Wind Corrected Munitions Dispenser. Some versions of the F-16 
employ an OBOGS type system. 

F-18C/D/E/F/G - The Boeing F/A-18 Hornet is a twin-engine carrier-capable multirole fighter 
jet, designed for fleet air defense, air superiority, and ground attack missions. The 
F/A-18C/D Hornet provided the baseline design for the F/A-18E/F Super Hornet, a 
larger, evolutionary redesign of the F/A-18. Compared to the Hornet, the Super Hornet is 
larger, heavier and has improved range and payload. The Boeing EA-18G Growler 
electronic jamming platform was also developed from the F/A-18E/F Super Hornet. The 
F-18E/F/G uses an OBOGS system to provide the crew with breathing oxygen. 

F-22 - The F-22A Raptor is a USAF fighter aircraft that uses stealth technology. It is primarily 
an air superiority fighter but has multiple capabilities including ground attack. It 
normally carries its munitions internally to preserve its stealth characteristics but can 
carry additional munitions on external hard points if required. The F-22 employs an 
OBOGS to provide oxygen to the pilot. 

F-35 - The F-35 Lightning II is a single-seat, single-engine, stealth capable military strike fighter 
aircraft currently in development for the USAF and other Services as well as several 
foreign countries. It is a multi-role aircraft that can accomplish close air support, tactical 
bombing, and air superiority. The F-35 employs an OBOGS to provide oxygen to the 
pilot. 

Failure Mode Effects and Criticality Analysis (FMECA) - FMECA was originally developed 
in the 1940s by the US military. It is an extension of failure mode and effects analysis 
(FMEA). FMEA is a bottom-up, inductive analytical method which may be performed at 
either the functional or piece-part level. FMECA extends FMEA by including a 
criticality analysis, which is used to chart the probability of failure modes against the 
severity of their consequences. The result highlights failure modes with relatively high 



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probability and severity of consequences, allowing remedial effort to be directed where it 
will produce the greatest value. 

Federal Acquisition Regulations - The principal set of rules in the Federal Acquisition 
Regulation System. This system consists of sets of regulations issued by agencies of the 
federal government of the United States to govern the acquisition process for goods and 
services. The FAR System regulates the activities of government personnel in carrying 
out that process. It does not regulate the purchasing activities of private sector firms, 
except to the extent that portions of the FAR are incorporated into government 
solicitations and contracts by reference. The FAR is codified in Title 48 of the United 
States Code of Federal Regulations; and the FAR and its agency supplements are said by 
the federal courts to have "the force and effect of law." Nearly all government agencies 
are required to comply with the FAR in the acquisition of services and goods. 

Fiscal Year (FY) - For the United States Government, the period covering 1 October to 30 
September (12 months). 

Fly-To- Warn / Fly-To-Fail - A design technique whereby a mission system, subsystem, or part 
will be considered to be operational until an external indication of an impending or actual 
partial or total performance malfunction is received. If a system is designed to be or 
shown to be inherently very reliable and maintenance free this technique can greatly 
reduce costs by the elimination of having to replace parts/sy stems on a schedule-based or 
use-based basis. Many modern complex systems employ this design philosophy. For 
example, commercial aircraft engines used to be removed, overhauled, and replaced 
strictly on an operating hour basis. Now they usually remain "on-wing" until a warning 
of an impending failure is received or an actual failure is experienced. Normally, 
employment of this technique requires that the system be very well understood and all its 
operating and failure modes be well characterized. 

Follow-On Operational Test and Evaluation - The Test and Evaluation efforts that may be 
necessary after the Full-Rate Production Decision Review to refine the estimates made 
during Operational Test and Evaluation, to evaluate changes, and to reevaluate the system 
to ensure that it continues to meet operational needs and retains its effectiveness in a new 
environment or against a new threat. 

Form 107, 107 Team - The Form 107, Request for Engineering Technical Assistance is used for 
two types of assistance needs: for Technical Assistance (TAR) and for Maintenance 
Assistance (MAR). A TAR is used for engineering support/disposition and a MAR 
requests depot maintenance action. The Form 107 provides advice, assistance, 
disposition, and training pertaining to installation, operation, and maintenance of 
equipment using authorized procedures. It can also provide authorization for one-time 
repairs or time definite repair opportunities beyond what is spelled out in existing 
technical orders and can also provide the one-time authority to use a specific 
part/commodity with defects or deviations beyond technical order limits and/or provide 
authorization for limited use of non-listed substitutes (supplies, components, support 
equipment, etc.) to prevent mission impairment. A multi-disciplinary "107 Team" may 
put together and can perform as a relatively long-term technical and maintenance task 
team depending on the severity and urgency of the problem to be addressed. 



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Full Operational Capability (FOC) - FOC is achieved when all intended users (by agreement 
between the developer and the user) have the intended operational capability. See entry 
for Initial Operational Capability. 

Functional Management Inspection (FMI) - An evaluation of a particular 
function/practice/program and how effectively it is being performed, sometime restricted 
to a particular sub-organization or location, or sometimes evaluating the totality of that 
function throughout a large organization. An FMI is normally conducted by an outside 
evaluation organization such as the Office of the Inspector General. Examples have 
included FMIs for all USAF Base Facility Energy programs, all Base Child Care 
Facilities throughout the Air Force, Intelligence Support to Systems Acquisition, etc. 

G-Suit - A flight suit worn by aircrew subject to high levels of acceleration force due to aircraft 
maneuvering. It is designed to prevent a loss of consciousness caused by the blood 
pooling in the lower part of the body when under acceleration, thus depriving the brain of 
blood which in turns leads to temporary hypoxia. A G-suit generally takes the form of 
tightly-fitting trousers fitted with inflatable bladders which, when pressurized through a 
G-sensitive valve, constrict on the abdomen and legs, thus restricting the draining of 
blood away from the brain during periods of high acceleration. In addition, in some 
modern fighters capable of very high sustained G maneuvers, the G-suit effect is 
augmented by a small amount of pressure applied to the lungs (partial pressure 
breathing), which also enhances resistance to high G. 

Goldwater-Nichols - "Shorthand" for the Goldwater-Nichols Department of Defense 
Reorganization Act of 1986, which reorganized the command structure of the DoD. It 
increased the powers of the Chairman of the Joint Chiefs of Staff and implemented some 
of the suggestions from The Packard Commission. Operational authority was centralized 
through the Chairman of the Joint Chiefs as opposed to the Military Service Chiefs. The 
Chairman was designated as the principal military advisor to the President, National 
Security Council, and Secretary of Defense. The Act established the position of 
Vice-Chairman and streamlined the operational chain of command from the President to 
the Secretary of Defense to the Unified Command Commanders (now Combatant 
Command Commanders). It also established certain Service headquarters functions as 
being under the sole purview of the Secretaries of the Military Services (removing the 
Military Chiefs of the Services from any formal role in these areas), including 
Acquisition, Comptroller, Information Management, Auditing, Public Affairs, and 
Legislative Affairs. See the entry for Packard Commission. 

Graywolf TG-501 - A multi-gas capable sensing monitor from GrayWolf Sensing Solutions, 
LLC. It is capable of measuring the presence/concentration of a wide variety of 
potentially toxic gases including Ozone, Ammonia, Sulfur Dioxide, Carbon Monoxide, 
Hydrogen Sulfide, Hydrogen Cyanide, Carbon Dioxide, Oxygen, etc. 

Halogenated Anesthetics - At room temperatures, halogenated anesthetics are typically clear, 
colorless, mainly non-odorous, and highly volatile liquids. Examples include isoflurane, 
halothane, enflurane, desflurane, and sevoflurane. 

Hardware-In-The-Loop - Hardware-In-the-Loop (HIL) is a form of real-time simulation. HIL 
differs from pure real-time simulation by the addition of a real component in the loop. 
The purpose of a Hardware-In-the-Loop system is to provide all of the electrical and 



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other stimuli needed to fully exercise a component (mechanical, electrical, hydraulic, or 
electromechanical). The effect (for the unit being evaluated) is that it "thinks" that it is in 
its actual intended environment (pressure, temperature, etc.) and all/most external input is 
provided via real hardware. 

Human Factors - The comprehensive integration of human capabilities and limitations 
(cognitive, physical, sensory, and team dynamic) into system design, development, 
modification, and evaluation to optimize human-machine performance for both operation 
and maintenance of a system. Human Factors Engineering designs systems that require 
minimal manpower, provide effective training, can be operated and maintained by users, 
and are suitable and survivable. 

Human System Integration (HSI) - A process to ensure systems are designed and developed 
that effectively and affordably integrate with human capabilities and limitations. The 
HSI process considers human factors engineering, manpower, personnel, training issues, 
and environment, safety and occupational health aspects. 

Hyperventilatory Response - Hyperventilation (or "overbreathing") in humans can be in 
response to stress or other conditions. Hyperventilation can cause symptoms such as 
numbness or tingling in the hands, feet and lips, lightheadedness, dizziness, headache, 
chest pain, spasm of hands and feet, slurred speech, and sometimes fainting. These 
effects are not caused by lack of oxygen or air. Rather, faster or deeper breathing than 
normal can cause excessive expulsion of circulating carbon dioxide. Lowering carbon 
dioxide reduces the acidity of the circulating blood. Low acidity (the proxy for low 
carbon dioxide levels) causes the brain's blood vessels to constrict, resulting in reduced 
blood flow to the brain and lightheadedness. The low acidity value resulting from 
hyperventilation also reduces the level of available calcium, which affects the nerves and 
muscles, causing constriction of blood vessels and tingling. 

Hypoxia - Hypoxia is a condition in which the body is deprived of adequate oxygen supply. 
The symptoms of generalized hypoxia depend on its severity and acceleration of onset. 
In the case of altitude sickness, where hypoxia develops gradually, the symptoms include 
headaches, fatigue, shortness of breath, a feeling of euphoria and nausea. Generalized 
hypoxia occurs in healthy people when they ascend to high altitude or when breathing 
mixtures of gases with a low oxygen concentration. Hypoxia can also occur when there 
is adequate oxygen, but poor tissue perfusion or when there is exposure to toxic levels of 
certain chemicals (e.g., Carbon Monoxide or Cyanide). 

Inherently Governmental Responsibility - In general, such inherently government functions 
would include those that substantially or wholly involve activities that: 

• Involve exercising the sovereign power of the federal government to include 
determining, protecting, or advancing United States interests by military, police, 
contract management action, or 

• Significantly affect the life, liberty, or property of private persons, or 

• Exert ultimate control over the disposition of federal property. 

Examples of functions considered to be inherently governmental functions or which the 
federal government has directed as to be treated as such include: 

• Direct conduct of criminal investigations. 



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• Control of prosecutions and performance of adjudicatory functions other than those 
relating to arbitration or other methods of alternative dispute resolution. 

• Command of military forces, especially the leadership of military personnel who 
are members of the combat, combat support, or combat service support role. 

• Conduct of foreign relations and the determination of foreign policy. 

• Determination of Agency policy, such as determining the content and application of 
regulations, among other things. 

• Determination of Federal program priorities for budget requests. 

• Direction and control of Federal employees. 

• Direction and control of intelligence and counter-intelligence operations. 

• The determination of what Government property is to be disposed of and on what 
terms (although an agency may give contractors authority to dispose of property at 
prices within specified ranges and subject to other reasonable conditions deemed 
appropriate by the agency). 

• Approval of Federal licensing actions and inspections. 

• Determination of budget policy, guidance, and strategy. 

Initial Operational Capability - The first attainment of the capability to employ effectively a 
weapon, item of equipment, or system of approved specific characteristics that is manned 
or operated by an adequately trained, equipped, and supported military unit or force. 

Initial Operational Test and Evaluation (IOT&E) - Dedicated operational test and evaluation 
conducted on production or production representative articles, using typical operational 
scenarios, to determine whether systems are operationally effective and suitable. It 
immediately precedes the full-rate production decision. IOT&E is conducted by an 
OT&E agency independent of the contractor, program management office, or developing 
agency. 

Integrated Caution, Advisory, and Warning (ICAW) - The F-22 ICAW system filters 
unnecessary detail and duplication to inform the pilot of a fault. This reduces pilot 
workload by presenting only what information regarding system and subsystem operation 
and status that the pilot needs to know. Up to 12 ICAW messages can be displayed at the 
same time. An ICAW warning to the pilot may be evidenced by an aural or visual 
indication or both. 

Integrated Product Team (IPT) - A multidisciplinary group of people who are collectively 
responsible for delivering a defined product or process. IPTs are used in complex 
development programs/projects for review and decision making. The emphasis of the 
IPT is on involvement of all stakeholders (users, customers, management, developers, 
etc.) in a collaborative forum. An IPT is empowered to make critical life cycle decisions 
for the development of a product or system. 

Ketones - An organic compound with the general formula of CnH2nO. Ketones are of great 
importance in industry and in biology. Examples include many sugars (e.g., fructose) 
and the industrial solvent acetone. Ketones are pervasive in nature and are necessary for 
photosynthesis to occur in plants. Ketones are produced on massive scales in industry as 
solvents, polymer precursors, and pharmaceuticals. In general, any hydrocarbon 
combustion process gives off a variety of ketones. Simple ketones, with a few 



172 



exceptions, are not highly toxic, which is a reason for their relatively wide-spread use as 
solvents. 

Key Performance Parameter (KPP) - Those attributes or characteristics of a system that are 
considered critical or essential to the development of an effective military capability. A 
KPP normally has a threshold, representing the required value, and an objective, 
representing the desired value. KPPs are contained in the Capability Development 
Document and the Capability Production Document and are included verbatim in the 
Acquisition Program Baseline. Certain KPPs may be "mandatory" or "selectively 
applied," depending on the system. 

Life Support System - A fighter aircraft life support system (such as that installed in the F-22) 
is intended to sustain the activities of and protect the life/health of the aircrew by 
providing a pressurized environment, heated/cooled and filtered breathing air as required, 
supplemental oxygen as needed, anti-G protection, anti-flash protection, and other 
support needed to enable the continued performance and sustain the life of the aircrew. 

Life Sustainment System - The life sustainment system includes the F-22 environmental 
control system plus the life support system. 

LOX System - Liquid oxygen (LOX) systems were commonly used in military aircraft to 
provide breathing oxygen to the crew, starting in the 1950s. While effective in meeting 
their purpose, aircraft LOX systems were logistically expensive and sometimes complex 
to support (each base had to have a liquid oxygen generating plant) and the aircraft 
systems were sometimes dangerous to maintain/replenish. Also, mission 
accomplishment was dependent on the availability of a liquid oxygen plant. For each 
tactical base, the LOX plants represented a single point of vulnerability against which an 
enemy could target. For these and other reasons the US Air Force began moving towards 
"self-sufficiency" for new-design aircraft in the 1980s. Each aircraft would generate its 
own needed breathing oxygen, thus decreasing overall mission vulnerabilities and 
reducing logistics footprint and cost for expeditionary forces. 

Manpower, Personnel, and Training (MPT) Factors - MPT factors are components of the 
discipline of human factors integration. They are usually considered early in the weapon 
system acquisition process, especially in the design of the system and specifically in the 
operator/sustainer- system interface. 

Mean Time Between Failures (MTBF) - The predicted (or experienced) elapsed time between 
inherent failures of a system during operation. MTBF can be calculated as the arithmetic 
mean (average) time between failures of a system. The definition of MTBF depends on 
the definition of what is considered a system failure. For complex, repairable systems, 
failures are considered to be those out of design conditions which place the system out of 
service and into a state for repair. Failures which occur that can be left or maintained in 
an unrepaired condition, and do not place the system out of service, are not considered 
failures. 

Milestone A - A DoD acquisition program milestone is a point at which a recommendation is 
made and approval sought regarding starting or continuing an acquisition program, i.e., 
proceeding to the next phase. Milestone A is that decision point that approves entry into 
the Technology Development phase. 



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Military Specification (Mil-Spec) - A document that describes the essential technical 
requirements for purchased materiel that is military unique or substantially modified 
commercial items. 

Military Standard (Mil-Std) - A document that establishes uniform engineering and technical 
requirements for military-unique or substantially modified commercial processes, 
procedures, practices, and methods. There are five types of defense standards: interface 
standards, design criteria standards, manufacturing process standards, standard practices, 
and test method standards. 

Mission Design Series - A series of numbers and letters that describe the basic mission of the 
aircraft, modifications to the aircraft, manufacturer, etc. These numbers and letters 
represent the Mission Design Series (MDS). All US military aircraft were given a 
two-part MDS symbol or designation when the Department of Defense unified all 
military aircraft designations under a common designation system. The first part is a 
letter which tells the kind of aircraft (mission) and the second part is a number which tells 
the model (model) of the aircraft. A third character (letter) designates the variant. For 
example, the MDS of F-15C indicates a fighter aircraft, 15 th fighter design, and the third 
variant. Some MDS variants represent only a paper proposal and may not have actually 
been flown, manufactured, or even fully designed, leading to "jumps" in the sequence of 
actual fielded MDS nomenclatures. 

Molecular Sieve Oxygen Generating Systems (MSOGS) - Molecular sieve oxygen generating 
systems are replacing liquid oxygen systems as the principal method for the production of 
breathable oxygen on-board military aircraft. These systems separate oxygen from 
aircraft engine bleed air by application of pressure swing adsorption technology. Oxygen 
is concentrated by preferential adsorption of nitrogen in a zeolite molecular sieve. The 
oxygen-rich product gas is breathed by the aircrew for the prevention of hypoxia at high 
altitudes. When compared to conventional liquid oxygen systems, MSOGS systems offer 
many benefits including reduced life cycle cost, reduced logistic support, increased 
aircraft versatility, and improved safety. 

The critical component of the system is the oxygen concentrator which separates oxygen 
from the aircraft engine bleed air (compressed air) by pressure swing adsorption 
technology. Nitrogen is preferentially adsorbed in the molecular sieve at moderate 
pressures (nominal 35 psig), thereby concentrating oxygen which is collected and 
provided to the aircrew. Subsequently, the nitrogen is released to the ambient 
atmosphere as a waste gas. Control of the oxygen concentration is accomplished by 
either diluting the product gas with cabin air or by varying one of the concentrator 
operating parameters such as cycle time. The concentrator need only be supplied engine 
bleed air and a small amount of electrical power to produce a continuous stream of 
concentrated oxygen. See OBOGS entry (below). 

Multi-RAE - A chemical/gas detection and monitoring system produced by RAE Systems. It is 
capable of reading substance amounts at the parts-per-billion level. MultiRAE detection 
systems were installed in F-22 test aircraft during the F-22 aircraft oxygen generation test 
program to help detect any contaminants. 

MV-22/CV-22 - The Bell-Boeing V-22 Osprey is a multi-mission, military, tilt rotor aircraft 
with both a vertical and short takeoff and landing capability. It is designed to perform 



174 



missions like a conventional helicopter with the long-range, high-speed cruise 
performance of a turboprop aircraft. The V-22 is used by the US Air Force (CV-22) and 
the US Marine Corps (MV-22). 

Neuro-protective - The effect of any chemical, biological molecule, or medical practice which 
has a protective effect in the nervous system against neurodegenerative disease, toxins, or 
brain injury. 

Neurotoxicity - Occurs when exposure to natural or artificial toxic substances (neurotoxins) 
alters the normal activity of the nervous system in such a way as to cause damage to 
nervous tissue. This can include disruption or the death of neurons, which are key cells 
that transmit and process signals in the brain and other parts of the human nervous 
system. Symptoms may appear immediately after exposure or be delayed. 

Nitrogen - A chemical element that is a colorless, odorless, tasteless, and mostly inert gas at 
standard conditions. It constitutes about 78 percent of the Earth's atmosphere by volume. 
Many industrially important compounds, such as ammonia, nitric acid, organic nitrates 
(propellants and explosives), and cyanides, contain nitrogen. It also occurs in all living 
organisms, primarily in amino acids and thus proteins. The human body contains about 
3% by weight of nitrogen. 

Non Developmental Item - Any previously developed item of supply used exclusively for 
government purposes by a Federal Agency, a State or Local Government, or a Foreign 
Government with which the United States has a mutual defense cooperation agreement. 
It also includes any item described above that requires only minor modifications or 
modifications of the type customarily available in the commercial marketplace in order to 
meet the requirements of the procuring department or agency. 

No Observed Adverse Effect Level - In toxicology it is specifically the highest tested dose or 
concentration of a substance at which no measureable adverse effect is found in exposed 
test organisms where higher doses or concentrations resulted in an adverse effect. 

On-Board Oxygen Generation System (OBOGS) - An OBOGS generates oxygen enriched air 
directly and in unlimited amounts on board aircraft to meet all the physiological needs 
(including breathable gas and anti-g protection) for the aircrew. An OBOGS can provide 
significant advantages over a stored-oxygen system (using either gaseous or liquid 
oxygen). In general an OBOGS requires much less maintenance than a comparable 
stored-gas system and does not have to be periodically replenished with oxygen. Rather, 
as long as the aircraft engines operate normally a steady supply of breathable, oxygen- 
rich air is provided. In an OBOGS an adsorbent is used to remove nitrogen from the air, 
which in turn enriches the oxygen concentration in the outlet air stream. Materials such 
as zeolite are commonly used to remove nitrogen and concentrate oxygen. See the 
Molecular Sieve Oxygen Generating Systems entry. 

Operational Test and Evaluation - The field test, under realistic conditions, of any item (or 
key component) of weapons, equipment, or munitions for the purpose of determining the 
effectiveness and suitability of the weapons, equipment, or munitions for use in combat 
by typical military users; and the evaluation of the results of such tests. 

Organic Polymer - A polymer is any of various chemical compounds made of smaller, identical 
molecules (called monomers) linked together. Organic polymers are carbon-based. 



175 



Some organic polymers, like cellulose, occur naturally, while others, like nylon, are 
artificial. Polymers have extremely high molecular weights, make up many of the tissues 
of organisms, and have extremely varied and versatile uses in industry, such as in making 
plastics, concrete, glass, and rubber. 

Organophosphate - The general name for esters of phosphoric acid. Many organophosphates 
are widely used as solvents, plasticizers, and extreme pressure additives to some 
lubricants (where they decrease wear of the parts of the gears exposed to very high 
pressures). However, organophosphates are also the basis of many insecticides, and 
herbicides. Many organophosphates are highly toxic and even at relatively low levels 
may be hazardous to human health. 

Oxygen Saturation - Oxygen saturation (also known as dissolved oxygen) is a relative measure 
of the amount of oxygen that is dissolved or carried in a given medium. It can be 
measured with a dissolved oxygen probe such as an oxygen sensor. In medicine, oxygen 
saturation refers to oxygenation, or when oxygen molecules enter the tissues of the body. 
In this case blood is oxygenated in the lungs, where oxygen molecules travel from the air 
and into the blood. Oxygen saturation measures the percentage of hemoglobin binding 
sites in the bloodstream occupied by oxygen molecules. 

Packard Commission - The President's Blue Ribbon Commission on Defense Management 
(also known as the Packard Commission) was commissioned to study several areas of 
management functionality within the Department of Defense. Chaired by David Packard, 
the Commission made several recommendations: (1) that defense appropriations should 
be passed by the United States Congress in two-year budgets rather than annual 
appropriations bills; (2) the creation of a "procurement czar," to be known as the Under 
Secretary of Defense for Acquisition and the creation of a clear hierarchy of acquisition 
executives and managers in each of the Services; (3) the Theater Commanders (today's 
Combatant Commanders) should report directly to the Secretary of Defense through the 
Chairman of the Joint Chiefs of Staff; and (4) the powers of the Chairman of the Joint 
Chiefs of Staff should be strengthened. Many of the recommendations by the 
commission were used when Congress passed the Goldwater-Nichols Act. See the entry 
for Goldwater-Nichols. 

Partial Pressure, Partial Pressure of Oxygen - The individual pressure exerted independently 
by a particular gas within a mixture of gases is the "partial pressure" of that gas. The air 
breathed by those residing within earth's biosphere is mixture of gasses (primarily 
nitrogen, oxygen, argon, and carbon dioxide). The total pressure generated by the air is 
due in part to nitrogen, in part to oxygen, and in part to each of the other constituent gases 
that make up the atmosphere. That part of the total pressure generated by oxygen is the 
"partial pressure" of oxygen. When the partial pressure of oxygen falls too low (caused 
by increasing altitude, in which the partial pressure of all the constituent gases falls; or 
without increasing altitude, by the percentage of oxygen in the surrounding air being 
reduced through some means) then humans suffer ill effects, the alleviation or prevention 
of which requires the provision of adequate amounts of supplemental breathing oxygen. 

Permissible Exposure Limit - The permissible exposure limit (PEL) is a regulatory limit for 
exposure of a worker to a chemical substance or physical agent. For chemicals, the limit 
is usually expressed in parts per million (ppm). Permissible exposure limits are 



176 



established by the Occupational Safety and Health Administration. A PEL is usually 
given as a time-weighted average (TWA), although some are short-term exposure limits. 
A TWA is the average exposure over a specified period of time, usually a nominal eight 
hours. This means that, for limited periods, a worker may be exposed to concentrations 
higher than the PEL, so long as the average concentration over eight hours remains lower. 
In contrast, a short-term exposure limit is one that addresses the average exposure over a 
15-30 minute period of maximum exposure during a single work shift. 

Petroleum, Lubricants, and Oils (POL) - A term sometimes used as a "shorthand" for the 
totality of petroleum derived products used on an aircraft, including jet fuel, engine oil, 
lubricating oils, some coolants, etc. 

Phosphorylated Butylcholinesterase (BChE) - Butyrylcholinesterase (BChE) is an enzyme 
that hydrolyses many different choline esters. Detection of phosphorylated BChE in 
human plasma can serve as an exposure biomarker of exposure to organophosphate 
pesticides and nerve agents. 

Plenum, Plenum Chamber - A pressurized housing containing a gas or fluid (typically air) at 
positive pressure (pressure higher than surroundings). The function of the plenum is 
often to equalize pressure for more even distribution, because of irregular supply or 
demand. For an OBOGS-type aircraft breathing system, the existence of and size of the 
plenum can determine the amount of residual breathing oxygen/air available to the 
aircrew in the event of an interruption of the primary gas supply stream feeding the 
plenum. 

Poly-Alpha-Olefin (PAO) - PAO is a polymer made by polymerizing an alpha-olefm. An 
alpha-olefm (or a-olefm) is an alkene where the carbon-carbon double bond starts at the 
a-carbon atom, i.e., the double bond is between the #1 and #2 carbons in the molecule. 
Many poly-alpha-olefms do not crystallize or solidify easily and are able to remain oily, 
viscous liquids even at lower temperatures. Low molecular weight poly-alpha-olefms are 
useful as synthetic lubricants such as synthetic motor oils for vehicles used in a wide 
temperature range, including aircraft jet engines. 

ppbRAE - A very sensitive device manufactured by RAE Systems for measuring volatile 
organic compounds (VOCs). It is capable of sensing VOC concentrations measured as 
low as one part per billion. It is used for various hazardous materials, Homeland 
Security, industrial hygiene, indoor air quality, and military applications. 

Pressure Breathing for G - A system/technique where the beneficial effects and actions of an 
anti-G suit is augmented by a small amount of pressure applied to the lungs (i.e., partial 
pressure breathing), which also enhances resistance to the high G-loads experienced by 
aircrew in some 4 th and 5 th generation fighters (e.g., the F-22 Raptor and F-35 Lightning 

ii). 

Pressure Swing Adsorption (PSA) - A technology used to separate some gas species from a 
mixture of gases under pressure according to the species' molecular characteristics and 
affinity for an adsorbent material. Special adsorptive materials (e.g., zeolites) are used as 
a molecular sieve, preferentially adsorbing the target gas species at high pressure. The 
process then swings to low pressure to desorb the adsorbent material. Pressure swing 
adsorption processes rely on the fact that under high pressure, gases tend to be attracted 



177 



to solid surfaces, or "adsorbed." The higher the pressure, the more gas is adsorbed; when 
the pressure is reduced, the gas is released, or desorbed. If a gas mixture such as air, for 
example, is passed under pressure through a vessel containing an adsorbent bed of 
synthetic zeolite that attracts nitrogen more strongly than it does oxygen, part or all of the 
nitrogen will stay in the bed, and the gas coming out of the vessel will be enriched in 
oxygen. When the bed reaches the end of its capacity to adsorb nitrogen, it can be 
regenerated by reducing the pressure, thereby releasing the adsorbed nitrogen. It is then 
ready for another cycle of producing oxygen enriched air. Using two or more adsorbent 
vessels allows near-continuous production of the target gas. 

Press-To-Test - A device controller (switch, button, etc.) designed so that when pressed it 
activates a test sequence and then reports to the operator (via noise, light, or other signal) 
on the current functionality of the device to which it is connected. 

Product Gas - With respect to the F-22 OBOGS the product gas is that produced and measured 
at the outlet of the OBOGS. Nominally, when the OBOGS is being commanded to 
produce the maximum amount of oxygen of which it is capable, the product gas should 
consist almost exclusively of oxygen, argon, and other trace amounts of inert gases. As 
the OBOGS is commanded to produce a lesser percentage of oxygen the product gas 
would have commensurately higher percentages of nitrogen. 

Program 6, Program 8 - Within the Department of Defense various broad categories of 
program spending are divided into "Major Force Programs" or MFPs. An MFP is an 
aggregation of Service and other component budget program elements that contain the 
resources required to achieve an objective or plan. It also reflects the fiscal year 
time-phasing of mission objectives to be accomplished and the means proposed for their 
accomplishment. All DoD funding resides in one of eleven MFPs. "Program 6" refers to 
the Research and Development budget. "Program 8" refers to the budget for Training, 
Medical, and Other General Personnel Activities. Other examples include Program 1 
(Strategic Forces), Program 2 (General Purpose Forces), and Program 11 (Special 
Operations Forces). 

Program Budget Decision (PBD) - Each budget year, many PBDs are issued by the Office of 
the Secretary of Defense. These PBDs modify the Military Services' suggested budgets 
(sometimes increasing resource allocations but, more often, reducing them). Once all of 
the PBDs are issued and resolved with the Services, the DoD budget is submitted to the 
Congress as a part of the President's Budget. 

Program Executive Officer - A key individuals in the DoD acquisition process. A Program 
Executive Officer (PEO) may be responsible for a specific program (e.g., the F-35), or for 
an entire portfolio of similar programs. Examples include the Air Force PEO for Space, 
who is responsible for all acquisition programs at the Air Force Space Command's Space 
and Missile Systems Center and the Navy PEO for Aircraft Carriers. In general, the 
System Program Manager reports to the Program Executive Officer who in turn reports to 
the Service Acquisition Executive. 

Program Objective Memorandum (POM) - The final product of the DoD Components' 
internal programming processes, the POM is submitted to the Secretary of Defense 
(SecDef) by the DoD Component heads (including the Secretary of the Air Force). The 
USAF POM recommends the USAF's total resource requirements and programs within 



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the parameters of SecDef s fiscal guidance and shows programmed needs for the six 
years of the Future Years Defense Program (FYDP) (i.e., in FY 2010, POM 2012-2017 
was submitted). The SecDef responds to the Component POMs by approving them, 
although subject to (many) directed modifications. After an iterative process between the 
Components and the Office of the Secretary of Defense regarding those modifications, 
the POM, as modified, becomes the Components' budgets that are submitted to SecDef 
and then to the Congress by the President. 

Pyrolysis, Pyrolysis Product - The thermochemical decomposition of organic material at 
elevated temperatures without the participation of oxygen. Pyrolysis differs from other 
high-temperature processes like combustion and hydrolysis in that it does not involve 
reactions with oxygen, water, or any other reagents. In practice, it is not possible to 
achieve a completely oxygen- free atmosphere and because some oxygen is present in any 
pyrolysis system, a small amount of oxidation occurs. Depending on the formulation of 
the organic material(s) undergoing pyrolysis, a wide variety of potentially harmful 
breakdown substances could be generated. 

Pulse Oximetry, Pulse Oximeter - Pulse oximetry is a non-invasive method allowing the 
monitoring of the oxygenation of a person's hemoglobin. A pulse oximeter is a device 
that indirectly monitors the oxygen saturation of the blood (as opposed to measuring 
oxygen saturation directly through a blood sample). It also measures the pulse rate. It is 
used to assess real-time oxygenation and determining the need for supplemental oxygen. 
A pulse oximeter can provide an instantaneous readout only or also record oxygen 
level/pulse rate over a period of time (hours/days). Most pulse oximeters are attached to 
a person's finger. Some caution should be used in interpreting results when attempting to 
use a finger-mounted oximeter as a proxy for brain oxygenation, as sometimes accuracy 
can be affected by hand/finger movement or reduced limb circulation due to tight fitting 
equipment/clothing or cold temperatures. A recording pulse oximeter (finger mounted) is 
used by all F-22 pilots to provide an instantaneous indication of possible reduced 
oxygenation and also by medical personnel (post flight) to detect and analyze possible 
reduced oxygenation events/periods, whether or not noticed by the pilot at the time. 

Quadrennial Defense Review (QDR) - A legislatively-mandated review of the US Department 
of Defense (DoD) strategies and priorities that is conducted every four years by the DoD. 
The QDR sets a long-term course for the DoD as it assesses priorities and challenges that 
the United States faces. It rebalances the DoD's strategies, capabilities, and forces to 
address current conflicts and future threats. The Quadrennial Defense Review Report is 
the main public document describing the military doctrine of the United States. 

Raptor Cough - A condition characterized by a repetitive, "dry" (unproductive) cough, 
experienced by a relatively large percentage of F-22 Raptor pilots after flights. 

Safety Critical - A term applied to a condition, event, operation, process, or item of whose 
proper recognition, control, performance, or tolerance is essential to safe system 
operation or use; e.g., safety-critical function, safety-critical path, safety-critical 
component/item. See the safety critical component/item entry. 

Safety Critical Component/Item - Any Safety Significant Item (see below) whose failure alone 
may result in death or loss of system (air vehicle). This includes any part, an assembly, 
installation equipment, launch equipment, recovery equipment, or support equipment for 



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an aircraft or aviation weapon system if the part, assembly, or equipment contains a 
characteristic any failure, malfunction, or absence of which could cause (1) a catastrophic 
or critical failure resulting in the loss of or serious damage to the aircraft or weapon 
system; (2) an unacceptable risk of personal injury or loss of life; or (3) an uncommanded 
engine shutdown that jeopardizes safety. Fracture critical and fatigue critical 
parts/assemblies are examples of specific characteristics that would cause an item to be 
considered as safety critical. 

Safety Critical Function - A function which, if performed incorrectly or not performed, may 
result in death, loss of system (such as an air vehicle), severe injury, severe occupational 
illness, or major system damage. Many safety critical components/items and safety 
significant items will contribute to a safety critical function. 

Safety Investigation Board (SIB) (Class A, Class E) - Following a mishap, separate safety and 
accident investigations are conducted. Safety investigations are conducted to prevent 
future mishaps. Safety investigations of weapons systems also assess possible force-wide 
implications on the combat readiness of these systems. By contrast, accident 
investigations are conducted to provide a report for public release. Safety investigations 
take priority over accident investigations because of the need to quickly assess the impact 
on a weapons system's ability to fulfill its national defense role. The SIB is convened 
within days of the mishap and is given approximately thirty days to return its assessment. 
The SIB Report is prepared in two parts. The first is purely factual, and the second is 
privileged, meaning it is to be used solely for mishap prevention and is restricted from 
release outside the Air Force. The factual part is passed to the accident investigation 
board and is incorporated in that report in its entirety. The privileged part contains 
testimony taken under promise of confidentiality and a record of the SIB's deliberations. 

Mishaps (and the SIBs that investigate them) are categorized by the severity of the 
mishap results. With regard to the SAB's F-22 Aircraft Oxygen Generation Study there 
have been two mishap types of interest. 

Class A: A mishap resulting in (1) direct mishap cost totaling $2,000,000 or more, (2) a 
fatality or permanent total disability, and/or (3) the destruction of a DoD aircraft. The 
SIB that investigated the 2010 fatal crash of an F-22 Raptor in Alaska was a Class A 
Safety Investigation Board. 

Class E: Events that do not meet reportable mishap classification criteria but nonetheless 
had a high potential for causing injury, occupational illness, or damage. Class E events 
are deemed important to investigate and trend for mishap prevention. Examples include 
unintentional departure from controlled flight, jet engine flameouts, loss of flight 
instruments, physiological events, etc. In general, these events may have been resolved 
without the loss or damage to an aircraft and without aircrew injury but the potential for 
one or both did exist. The (to date) two SIBs (one convened by Air Combat Command 
and one by Pacific Air Forces) that have examined the series of hypoxia incidents in the 
F-22 Raptor have been Class E Safety Investigation Boards. 

Safety of Flight - A safety of flight item is one whose failure could cause loss of an aircraft or 
aircrew, or cause inadvertent store release. A loss could occur either immediately upon 
failure or subsequently if the failure remained undetected. 



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Safety Significant - When used to qualify an object, such as a system, structure, component, or 
accident sequence, this term identifies that object as having an impact on safety, whether 
determined through risk analysis or other means, which exceeds a predetermined 
significance criterion. 

Safety Significant Item - An item which contributes to a safety critical function. 

Short Term Exposure Limit (STEL) - A term used in occupational health, industrial hygiene, 
and toxicology. The STEL may be a legal limit in the United States for exposure of a 
worker to a chemical substance. The Occupational Safety and Health Administration has 
set STELs for many substances. For chemicals, STEL assessments are usually done for 
15 minutes and expressed in parts per million. Usually a short-term exposure limit 
addresses the average exposure over a 15-30 minute period of maximum exposure during 
a single work shift. 

Spirometry - A common pulmonary function test that measures lung function, specifically the 
amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry 
is used in assessing conditions such as asthma, pulmonary fibrosis, and cystic fibrosis. 
The spirometry test is performed using a device called a spirometer. The test is highly 
dependent on patient cooperation and effort, and is normally repeated at least three times 
to ensure reproducibility. 

Summa Canister - A stainless steel electro-polished (or "summa" polished) passivated vacuum 
vessel used to collect a whole air sample. To collect a sample, the summa canister valve 
is opened and the canister is left in a designated area for a period of time (sometimes very 
short, to "grab" an air sample) to allow the surrounding air to fill the canister and achieve 
a representative sample. The valve is then closed and the canister is sent to a laboratory 
for analysis. 

System Program Office (SPO) - A Department of Defense system program office normally is 
responsible for the development, acquisition, and support of a weapon system. It 
provides program direction and logistics support as the single face to the customer. 
Among other tasks, a SPO is responsible for acquisition, systems engineering and depot 
repair support; manages equipment spares; provides storage and transportation; and 
accomplishes modifications and equipment replacement to maintain the weapons system 
throughout its life. The SPO is headed by the System Program Manager and is the single 
Point of Contact with industry, government agencies, and other activities participating in 
the system acquisition and sustainment processes. 

Systems Engineering - An interdisciplinary field of engineering that focuses on how complex 
engineering projects should be designed and managed over the life cycle of the system. 
Issues such as logistics, the coordination of different teams, and automatic control of 
machinery become more difficult when dealing with large, complex projects. "Systems 
engineering," in this sense of the term, refers to the distinctive set of concepts, 
methodologies, organizational structures, etc., that have been developed to meet the 
challenges of engineering very complex functional physical systems. 

T-6 - The T-6 Texan II is a two-seat aircraft that is used by the US Air Force and US Navy to 
perform primary flight training for new pilots and weapon system operators. The T-6 is 



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powered by a single turbo-prop engine and utilizes an OBOGS system for production of 
breathing oxygen for the crew. 

Temporary Emergency Exposure Limit (TEEL) - TEELs are guidelines designed to predict 
the response of members of the general public to different concentrations of a chemical 
during an emergency response incident. TEELs estimate the concentrations at which 
most people will begin to experience health effects if they are exposed to a hazardous 
airborne chemical for a given duration. TEELs have been established for over 3,000 
chemicals. A chemical may have up to three TEEL values, each of which corresponds to 
a specific tier of health effects: 

• TEEL-3 is the airborne concentration of a substance above which it is predicted that 
the general population, including susceptible individuals, could experience life- 
threatening adverse health effects or death. 

• TEEL-2 is the airborne concentration of a substance above which it is predicted that 
the general population, including susceptible individuals, could experience irreversible 
or other serious, long-lasting, adverse health effects or an impaired ability to escape. 

• TEEL-1 is the airborne concentration of a substance above which it is predicted that 
the general population, including susceptible individuals, could experience notable 
discomfort, irritation, or certain asymptomatic, non-sensory effects. However, these 
effects are not disabling and are transient and reversible upon cessation of exposure. 

Terms of Reference - A statement of the background, objectives, and purpose of a program, 
project, or proposal which shows how the scope will be defined, developed, and verified. 

Thermal Transport Medium - A substance used to transfer heat energy from one location to 
another in a system. For example, in an automobile, radiator coolant (sometimes water) 
is used to move excess heat from the engine block to the radiator where it can be 
transferred to the atmosphere. 

Threshold Limit Value (TLV) - A level to which it is believed a worker can be exposed day 
after day for a working lifetime without adverse health effects. It is an estimate based on 
the known toxicity in humans of a given chemical substance. The TLV for chemical 
substances is defined as a concentration in air, typically for inhalation or skin exposure. 

Toxicity - Toxicity is the degree to which a substance can be poisonous. The toxicity of a 
substance is normally dose-dependent; even water can lead to water intoxication when 
taken in large enough doses, whereas for even a very toxic substance (e.g., cyanide) there 
is a dose below which there is no detectable toxic effect. Toxicity of a substance can be 
affected by many different factors, such as the pathway of administration (whether the 
toxin is applied to the skin, ingested, inhaled, or injected), the time of exposure (acute, 
intermediate or chronic exposure), the number of exposures (a single dose or multiple 
doses over time), the physical form of the toxin (solid, liquid, or gas), the genetic makeup 
of an individual, an individual's overall health, and many others. 

Toxic Level of Contaminant - A level of a given contaminant that is likely to produce a defined 
degree of biological harm within a specified period of exposure. 

TOXLINE - A toxicology database that provides bibliographic information covering the 
biochemical, pharmacological, physiological, and toxicological effects of drugs and other 
chemicals. It contains over 4 million bibliographic citations. 



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TOXNET - The TOXicology Data NETwork is a cluster of databases covering toxicology, 
hazardous chemicals, environmental health, and related areas. TOXNET provides free 
access to and easy searching of a large number of toxicology databases. 

Tricresyl Phosphate (TCP) - An organophosphate compound that is a colorless, viscous liquid 
that is almost insoluble in water. TCP is used as a plasticizer and in many other 
applications including as a hydraulic fluid and a heat exchange medium. It is also used as 
an additive in turbine engine oil. 

Volatile Organic Compound (VOC) - VOCs are chemicals (both naturally occurring and 
man-made) with a high vapor pressure at room-temperature conditions. Their high vapor 
pressure results from a low boiling point, which causes large numbers of molecules to 
evaporate from the liquid or solid form of the compound and enter the surrounding air. 
Many VOCs are dangerous to human health or cause harm to the environment at high 
concentrations. 

Work Breakdown Structure (WBS) - A decomposition of a program/project into smaller 
components that defines and groups a project's discrete work elements in a hierarchy of 
levels that helps organize, rank by level, and define the total work scope of the project. A 
WBS element may be a product, data, rank by level, a service, or any combination. A 
WBS also provides the necessary framework for detailed cost estimating and control 
along with providing guidance for schedule development and control. 

Zeolite - Zeolites are microporous, aluminosilicate solids commonly used as commercial 
adsorbents. They are also known as "molecular sieves." The term molecular sieve refers 
to a particular property of these materials, i.e., the ability to selectively sort molecules 
based primarily on a size exclusion process. Zeolites are widely used as ion-exchange 
beds in domestic and commercial water purification, softening, and other applications. In 
chemistry, zeolites are used to separate molecules (only molecules of certain sizes and 
shapes can pass through), and as traps for molecules so they can be analyzed. 
Zeolite-based oxygen concentrator systems are widely used to produce medical-grade 
oxygen. The zeolite is used as a molecular sieve to create purified oxygen from air using 
its ability to trap impurities, in a process involving the adsorption of nitrogen, leaving 
highly purified oxygen and up to 6% argon. OBOGS use synthetic zeolites to remove 
nitrogen from compressed air in order to supply oxygen for aircrews at high altitudes. 
This leaves an oxygen-rich mixture (up to 94% oxygen plus about 6% argon, an inert 
gas). 

Zirconia Oxygen Sensor - An electronic device that measures the proportion of oxygen in the 
gas being analyzed. They are used for oxygen monitoring and control purposes. The 
sensing element is made with a zirconia ceramic coated on both the sensing and reference 
sides with a thin layer of platinum. The most common application is to measure the 
exhaust gas concentration of oxygen for internal combustion engines in automobiles and 
other vehicles. Divers and other users for whom percentage of oxygen is very important 
also use a similar device to measure the partial pressure of oxygen in a breathing gas. 



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Appendix M: Acronyms and Abbreviations 



@ At 

& And 

% Percent 

# Number 

$ Dollars 

Feet 

|Li Micro 

|Lig/m3 Micrograms per Cubic Meter 

1FW 1 st Fighter Wing 

9 th AF/SE 9 th Air Force Directorate of Safety 

59 th MDTS 59 th Diagnostics and Therapeutics Squadron 

AB Afterburner 

A/C, a/c Aircraft 

ACC Air Combat Command 

ACGIH American Conference of Industrial Hygienists 

ACH Analysis of Competing Hypotheses 

ACM Air Cycle Machine 

ACS Assistant Chief of Staff 

AETC Air Education and Training Command 

AETC/A3 Air Education and Training Command's Directorate of 

Intelligence, Operations and Nuclear Integration 

AETC/SG Air Education and Training Command's Office of the 

Surgeon General 

AF/A3/5 Air Force Deputy Chief of Staff for Air, Space, and 

Information Operations, Plans and Requirements 

AF/A4/7 Air Force Deputy Chief of Staff for Logistics, 

Installations, and Mission Support 

AF/A5R HQ US AF Director of Operational Capability 

Requirements 

AF/A9 HQ USAF Directorate of Studies & Analyses, 



185 



Assessments and Lessons Learned 
AFB Air Force Base 

AF/CC-SA Special Assistant to the AF Chief of Staff 

AFETS Air Force Engineering and Technical Services 

AFFTC Air Force Flight Test Center 

AFHSIO Air Force Human Systems Integration Office 

AFI Air Force Instruction 

AFIT Air Force Institute of Technology 

AF/JA Air Force Judge Advocate General 

AFLCMC Air Force Life Cycle Management Center 

AFMC Air Force Materiel Command 

AFMC/EN AFMC Directorate of Engineering and Technical 

Management 

AFMC/ENS Systems Engineering Division of the AFMC Directorate 

of Engineering and Technical Management 

AFMC/SE Air Force Material Command Director of Safety, 

AFMC Directorate of Safety 

AFMC/SG Air Force Materiel Command Surgeon General, 

Office of the AFMC Surgeon General 

AFRes Air Force Reserve 

AFRL Air Force Research Laboratory 

AFSC Air Force Safety Center 

AFSC Air Force Specialty Code 

AFSC/SEF AF Safety Center, Aviation Safety Division 

AF/SG Air Force Surgeon General, Office of the AF Surgeon 

General 

AF/ST Air Force Chief Scientist, Office of the AF Chief 

Scientist 

AGL Above Ground Level 

AGCAS Automatic Ground Collision Avoidance System 

AIP Acquisition Improvement Program 

AL Armstrong Laboratory 

Alpha Angle-of- Attack 

AMDS Aerospace Medicine Squadron 



186 



AMXS 

AOG 

AOG 

APOM 

Apr 

APU 

AR, Ar 

ARC 

ARIP 

A/S 

ASBREM 

ASC 

ASCC 

ASD 

ASHRAE 

ASIC 
ATAGS 
ATF 
Aug 

AUTO, Auto 
B 

BAR 

BFM 

BIT 

BOS 

BRAC 

BRAG 

Brig Gen 

CA 

CA 



Aircraft Maintenance Squadron 
Aircraft Oxygen Generation 
Air Operations Group 

Amended Program Objective Memorandum 
April 

Auxiliary Power Unit 
Argon 

Air Recharge Compressor 

Advanced Medium-Range Air-to-Air Missile 
(AMRAAM) Vertical Eject Launcher (AVEL) 
Replacement instrumentation Package (ARIP) 

Airspeed 

Armed Services Biomedical Research Evaluation and 
Management 

Aeronautical Systems Center 

Air Standardization Coordinating Committee 

Aeronautical Systems Division 

American Society of Heating, Refrigerating and Air 
Conditioning Engineers 

Air and Space Interoperability Council 

Advanced Technology Anti-Gravity Suit 

Advanced Tactical Fighter 

August 

Automatic 

Billion 

Broad Area Review 

Basic Fighter Maneuvers 

Built-in-Test 

Backup Oxygen System 

Base Realignment and Closure 

Breathing Regulator/Anti-G 

Brigadier General 

California 

Cabin Altitude 



187 



Capt Captain 

CFD Computational Fluid Dynamics 

Chem/Bio Chemical/Biological 

Ci Maximum Measured Concentration of Each Chemical 

CLSS Contractor Logistics Sustainment and Support 

CNS Central Nervous System 

Co Company 

CO Colorado 

CO Carbon Monoxide 

C02, C0 2 Carbon Dioxide 

Col Colonel 

Cone Concentration 

Config Configuration 

COTS Commercial Off the Shelf 

CPK Coburn, Foster, & Kane 

CRU Crew Regulator Unit 

CS AF Chief of Staff of the Air Force 

CTF Combined Test Force 

Cu/in Cubic Inches 

DAB Defense Acquisition Board 

DC District of Columbia 

DCS Deputy Chief of Staff 

Dec December 

deg Degree, Degrees 

Dem/V al Demonstration/Validation 

DNA Deoxyribonucleic Acid 

DoD, DOD Department of Defense 

DoDD Department of Defense Directive 

DoDI Department of Defense Instruction 

DoE Department of Energy 

Dr Doctor 

DSTO Defence Science and Technology Organization 

DTC Data Transfer Cartridge 



188 



D-Tube Desorption Tube 

EBIT Extended Built In Test 

ECS Environmental Control System 

Ed, ed., eds. Editor, Editors 

e.g. For Example 

Elmo Elmendorf Air Force Base 

EMD Engineering and Manufacturing Development 

EOS Emergency Oxygen System 

EPA Environmental Protection Agency 

ESOH Environment, Safety, and Occupational Health 

ETR Engine Thrust Request 

F Fahrenheit, degrees Fahrenheit 

FAA Federal Aviation Administration 

FAR Federal Acquisition Regulations 

FFRDC Federally Funded Research and Development Center 

FL Flight Level 

FL Florida 

FMECA Failure Mode Effects and Criticality Analysis 

FOC Full Operational Capability 

FOT&E Follow-On Test and Evaluation 

FOUO For Official Use Only 

FRP Full Rate Production 

FS Fighter Squadron 

ft Feet, Foot 

FW Fighter Wing 

FY Fiscal Year 

g gram 

G, g Gravity, Force of Gravity 

GA Georgia 

GABA Gamma- Aminobutyric Acid 

Gamma Flight Path Angle 

GAO Government Accountability Office 

GCAS Ground Collision Avoidance System 



189 



Gen 


General 


Govt 


Government 


GPS 


Global Positioning System 


H20, H 2 


Water 


HAF 


Headquarters United States Air Force 


Hg 


Mercury 


HIL 


Hardware-in-the-Loop 


HOX 


High Pressure Oxygen 


HPOX 


High Pressure Oxygen 


HPW 


Human Performance Wing 


HPWE 


High Pressure Water Extractor 


HRS 


Hours 


HSC 


Human Systems Center 


HSI 


Human Systems Integration 


HSIO 


Human Systems Integration Office 


HX 


Heat Exchanger 


ICAW 


Integrated Caution/ Advisory/Warning 


ICAWS 


Integrated Caution/Advisory/Warning Syst< 


ID 


Identify 


In, in 


inch, inches 


Inc 


Incorporated 


INC, Inc 


Increment 


IOC 


Initial Operational Capability 


IOT&E 


Initial Test and Evaluation 


IPT 


Integrated Product Team 


ITAR 


International Traffic in Arms Regulations 


ITB 


Integrated Terminal Block 


JPO 


Joint Program Office 


JSF 


Joint Strike Fighter 


K 


Thousand 


KCAS 


Knots Calibrated Air Speed 


KIO 


Knock It Off 


LAB 


Line Abreast 



190 



LED 


Light Emitting Diode 


LOX 


Liquid Oxygen 


1pm 


Liters per Minute 


LPWE 


Low Pressure Water Extractor 


LRIP 


Low Rate Initial Production 


LSS 


Life Support System, Life Sustainment System 


Lt Col 


Lieutenant Colonel 


Lt Gen 


Lieutenant General 


M 


Mach Number 


M 


Million 


m 


Cubic Meter 


Maj 


Major 


Maj Gen 


Major General 


MAX, Max 


Maximum 


MBIT 


Maintenance Built In Test 


MCM 


Molecular Characterization Matrix 


MD 


Doctor of Medicine 


MD 


Maryland 


MDS 


Mission Design Series 


MDTS 


Diagnostics and Therapeutics Squadron 


MFV 


Multi Function Valve 


mg/m 


Milligrams per Cubic Meter 


MIL, Mil 


Military 


Mil-Spec, MIL-SPEC 


Military Specification 


MIL-STD, Mil-Std 


Military Standard 


mm 


Millimeter, Millimeters 


mm/Hg 


Millimeters of Mercury 


MPH 


Master of Public Health 


MPT 


Manpower, Personnel, and Training 


Mr 


Mister 


MSL 


Mean Sea Level 


Msn, MSN 


Mission 


MSOGS 


Molecular Sieve Oxygen Generating System 



191 



MTBF Mean Time Between Failures 

MXG Maintenance Group 

MY Multi Year 

N, N2 Nitrogen 

N/A Not Applicable 

NASA National Aeronautics and Space Administration 

NAVAIR Naval Air Systems Command 

NAWC Naval Air Warfare Center 

n.d. not dated, no date 

NDI Non Developmental Item 

NFF No Fault Found 

NIOSH National Institute for Occupational Safety and Health 

nm Nautical Miles 

No. Number 

Nov November 

NRC National Research Council 

NTPD Normal Temperature and Pressure, Dry 

NzW Load Factor Normal to the Flight Path 

O Oxygen Partial Pressure 

02, 02 Oxygen 

OBIGGS On-Board Inert Gas Generating System 

OBOGS On-Board Oxygen Generation System 

OCOSR Overseas Contingency Operations Supplemental Request 

OCR Office of Collateral Responsibility 

Oct October 

OGADS Oxygen Generating and Distribution System 

OH Ohio 

O&M Operations and Maintenance 

OPR Office of Primary Responsibility 

OSD Office of the Secretary of Defense 

OSHA Occupational Safety and Health Administration 

OT&E Operational Test and Evaluation 

OTI One Time Inspection 



192 



OUSD (AT&L) Office of the Under Secretary of Defense (Acquisition, 





Technology and Logistics ^ 

X VvllllV/lV/ t Y , L4XJ.V-J- 1 — > V/ £~ 1 JllVJ 1 


Ox. Oxv 


Oxv*?en 

vy / v y civil 


p 


Pressure 

X 1 vJ J LAX w 


PAO 


Polv- Alnha-Olefin Polvalnhaolefin 




Partial Pressure of Oxv*?en in Arterial Rlood 

X CI 1 1 1 CI 1 X 1 VJ J C-l 1 V_/X V/ A V uvll 111 ± 11 IvllUl X-/ 1_V_/V/ V-l. 


PB 


President's Budget 


PBD 


Program Rud*?et Decision 

X 1 WC1U111 !_/ ClClC V I -L/ VVllJlVyll 


PBG 


Pressure Rreathin** for Ct 

X 1 VkJuUl v \—t 1 VvClLlllll £1 1U1 VJ 


PBL 


Performance Based Logistics 


PEL 


Permissible Exposure Limit 


POC 


Point of Contact 


POL 


Petroleum, Oil, and Lubricants 


POM 


Program Objective Memorandum 


PP 


Pa*?e na^es 


DDb 


Parts per Billion 


DDbV 
PP" 


Parts ner Rillion bv Volume 

X CV1 CkJ UV1 1_/1111U11 J vlUlllv 


DDm 


Parts per Million 


PP0 2 


Partial Pressure of Oxygen 


PRTV 


Production Representative Test Vehicle 


PRV 


Pressure Relief/Regulator Valve 


PSA 


Pressure Swin*? Adsomtion 

X IvouUl v Will cl ilcl JUl U 11 Wll 


PSI Dsi 


Pounds ner Snuare Tnch 

X V C-l 1 1 VI kJ L/C/1 k_J C| C-l Cll Vv 1 1 1 C/ 1 1 


PSID Dsid 


Pounds npr Snnarp Inch Differential 

X W C-l 1 1 d kj UC/1 kJ CI LI CI 1 C 1 1 1 C 1 1 L^r 11 Vv 1 1 L 1 CI 1 


PSIG, psig 


Pound per Square Inch Gauge 


Pulse-Ox 


Pulse Oximeter 

X C-l 1 J V Vy Allllv Lvl 


PVCV 


Pressurization and Vent Control Valve 


PVI 


Pilot Vehicle Interface 


QDR 


Quadrennial Defense Review 


RCCA 


Root Cause Corrective Action 


R-D 


TxPiniH T^ppnmTYrpssifYn 


RDT&E 


Research, Development, Test, and Evaluation 


Reg 


Regulator 




193 



Regen Regenerative 

REOS Regulated Emergency Oxygen System 

Ret Retired 

RQ Respiratory Quotient 

RTA Replacement Test Aircraft 

RTF Return to Fly 

SAB Scientific Advisory Board 

SAF Secretary of the Air Force, Air Force Secretariat 

SAF/AQ Assistant Secretary of the Air Force for Acquisition 

SAF/AQR Deputy Assistant Secretary of the Air Force for Science, 

Technology and Engineering 

SAF/AQX Deputy Assistant Secretary for Acquisition Integration 

SAF/FM Assistant Secretary of the Air Force for Financial 

Management and Comptroller 

SAF/IE Assistant Secretary of the Air Force for Installations, 

Environment, and Logistics 

SAF/OS Office of the Secretary of the Air Force 

SCF Safety Critical Function 

SCI Safety Critical Item 

SE Safety 

sec second, seconds 

SecAF Secretary of the Air Force 

Sep September 

SES Stored Energy System 

SES Senior Executive Service 

SG Surgeon General 

SIB Safety Investigation Board 

SMAC Spacecraft Maximum Allowable Concentration 

SN, s/n Serial Number 

SOV Shut-Off Valve 

SPEC, Spec Specification 

SPO System Program Office 

SSI Safety Significant Item 



194 



S&T 


Science and Technology 


STANAG 


Standardization Agreement 


STD, Std 


Standard 


s/w 


Software 


T 


Temperature 


T&E 


Test and Evaluation 


TCE 


Trichloroethylene 


TCP 


Tricrysel-Phosphate 


TEEL 


Temporary Emergency Exposure Limit 


TIC 


Toxic Industrial Compound 


TLSS 


Tactical Life Support System 


TLV 


Threshold Limit Value 


TMM 


Thermal Management Mode 


T/P/O 


Temperature/Pressure/Oxygen Partial Pressure 


TO 


Technical Order 


TOCP 


Triorthocresyl Phosphate 


TOR, TORs 


Terms of Reference 


Tox 


Toxicology, Toxin 


TR 


Technical Report 


TRL 


Technology Readiness Level 


TSPR 


Total System Performance Responsibility 


TSSR 


Total System Support Responsibility 


TST 


Test 


TW 


Test Wing 


TWA 


Time Weighted Average 


TX 


Texas 


U.S., US 


United States 


USAARL 


United States Army Aeromedical Research Laboratory 


USAF 


United States Air Force 


USAFR 


United States Air Force Reserve 


USAFSAM 


United States Air Force School of Aerospace Medicine 


USMC 


United States Marine Corps 


USN 


United States Navy 



195 



VA 


Virginia 


VADM 


Vice Admiral 


VOC 


Volatile Organic Compound 


Vs. 


Versus 


W/,w/ 


With 


WAM 


Warm Air Manifold 


WPAFB 


Wright-Patterson Air Force Base 


WUT 


Wind Up Turn 


YF 


Prototype Fighter 


Zulu 


Greenwich Mean Time 



Appendix N: Bibliography 



This bibliography is a list of materials that informed the Aircraft Oxygen Generation 
(AOG) Study Panel members' deliberations during the course of this Study. These represent 
almost all of the materials (briefings, papers, articles, data, etc.) made available to members of 
the AOG Study during the preparation for and conduct of the Study. Many were provided by 
outside organizations/individuals that briefed or otherwise informed the Study Panel and some 
were contributed by the Panel members themselves. In general these materials were provided as 
background information or as briefings during various fact finding trips or meetings undertaken 
by the Study Panel members. Many are not available for distribution beyond the Air Force 
Scientific Advisory Board as they contain classified, export controlled, proprietary, safety 
privileged, and/or For Official Use Only (FOUO) information. 

Notes: The references are listed by author(s) and date (if no date then "n.d."). If no 
author is cited then the document is ordered by the title of the document. 

711 th HPW Physiologic Assessment Team. (2012, January). Comparison of Event Rates: Pre 
F-22 Stand-down vs Post Stand-up. Briefing slides presented to the AOG Study Panel of the AF 
SAB during fact-finding meeting at Crystal City, VA. 

Abou-Donia, M. (2003). Organophosphorus Ester-Induced Chronic Neurotoxicity. Archives of 
Environmental Health, 58 (8), 484-497. 

Abou-Donia, M. (2005). Organophosphorus Ester-Induced Chronic Neurotoxicity. Journal of 
Occupational Health & Safety— Australia/New Zealand, 21 (5), 408-432. 

Abraini, J., Kriem, B., Balon, B., Rostain, J-C, & Risso, J-J. (2003). Gamma-aminobutyric Acid 
Neuropharmacological Investigations on Narcosis Produced by Nitrogen, Argon, or Nitrous 
Oxide. Anesthesia & Analgesia, 96 (3), 746-749. 

AC 60 and AC 172 Initial Assessment, (n.d.). Document provided to the AOG Study Panel of 
the AF SAB during fact-finding meeting at Crystal City, VA. 

Adams, W. (2003). Relation of Pulmonary Responses Induced by 6.6-H Exposures to 0.08 PPM 
Ozone and 2-H Exposures to 0.30 PPM Ozone Via Chamber and Face-mask Inhalation. 
Inhalation Toxicology, 15, 745-759. 

Aerospace Medical Association. (1953). Aviation Toxicology. New York, NY: Blakiston. 

Air Force Materiel Command. (2010, June). Acquisition Sustainment Tool Kit (ASTK) 
Kneepad Checklist. Wright-Patterson AFB, OH: Author. Document provided to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Air Force Materiel Command. (2011, January). Implementation Plan for Human Systems 
Integration (Version 1.0). Wright-Patterson AFB, OH: Author. Document provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 



197 



Air and Space Interoperability Council. (1988). The Minimum Quality Criteria for On-Board 
Generated Oxygen (ADVISORY PUBLICATION ACS (ASMG) 4060). Washington, DC: 
Author. 

Air Standardization Coordinating Committee. (2008, February). Minimum Physiological 
Requirements for Aircrew Demand Breathing Systems (Air Standard 61/101/6A). Washington, 
DC: Author. 

Air Standardization Coordinating Committee. (2010, February). Minimal Protection for Aircrew 
Exposed to Altitude Above 50,000 Feet (Air Standard 61/101/1C Change 1). Washington, DC: 
Author. 

Alexis, N., Lay, J., Hazucha, M., Harris, B., Hernandez, M., Bromberg, P., Kehrl, H., 
Diaz-Sanchez, D., Kim, C, Devlin, R., & Peden, D. (2010). Low-level Ozone Exposure Induces 
Airways Inflammation and Modifies Cell Surface Phenotypes in Healthy Humans. Inhalation 
Toxicology, 22 (7), 593-600. 

American Conference of Governmental Industrial Hygienists. (2001). Triorthocresyl Phosphate. 
In: Documentation of the Threshold Limit Values and Biological Exposure Indices (7th ed.). 
Cincinnati, OH: Author. 

American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. (2007). Air 
Quality Within Commercial Aircraft (ASHRAE Standard 161-2007). Atlanta, GA: Author. 

American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. (2009). Air 
Quality Within Commercial Aircraft (Addenda A and B to ASHRAE Standard 161-2007). 
Atlanta, GA: Author. 

Architzel, D. (2011, July 29). Aircrew Exposure to Oil Fumes in Military Aircraft. 
Correspondence to Mr. Christopher Witkowski, Association of Flight Attendants. Patuxent 
River MD: Naval Air Systems Command. 

Anderol, Inc. (2007, August). Material Safety Data Sheet: ROYCO 481. Document provided to 
the AOG Study Panel of the AF SAB. 

Atlantic Equipment Engineers (2000). Material Safety Data Sheet: Titanium Diboride Powder 
(C.A.S. Number: 12045-63-5). Bergenfield, NJ: Author. 

Balouet, J., Hoffman, H., & Winder, C. (1999, October). A viation and Exposure to Toxic 
Chemicals. World Aviation Congress & Exposition at San Francisco, CA (Aircraft Operations 
Session, SAE Paper No. 1999-01-5603). 

Beaman, J. (1985). A Dynamic Model of a Pressure Swing Oxygen Generation System. Journal 
of Dynamic Systems, Measurement, and Control 107, 111-116. 

Beaman, J., Healey, A., & Warlin, J. (1983). A Dynamic Model of a Molecular Sieve Bed with 
Nonlinear and Coupled Isotherms. Journal of Dynamic Systems, Measurement, and Control, 
105,265-271. 

Behnke, A., & Yarbrough, O. (1939). Respiratory Resistance, Oil- Water Solubility, and Mental 
Effects of Argon, Compared with Helium and Nitrogen. American Journal of Physiology, 126 
(2), 409-415. ~ 



198 



Benignus, V. (1994). Behavioral Effects of Carbon Monoxide: Meta Analyses and 
Extrapolation. Journal of Applied Physiology, 79 (3), 1310-1316. 

Benjamin, C, Edwards, B., Marchiando, A., Profenna, L., Louis, D., Ott, D., & Mattie, D. (2011, 
August). F-22 Response Checklist for Operational Bases. Briefing provided to AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Bennett, P. (1963). Prevention in Rats of Narcosis Produced by Inert Gases at High Pressures. 
American Journal of Physiology, 205 (5), 1013-1018. 

Bennett, P. (1965). Cortical CO2 and O2 at High Pressures of Argon, Nitrogen, Helium and 
Oxygen. Journal of Applied Physiology, 20 (6), 1249-1252. 

Bentin, S., Collins, G., & Adam, N. (1978). Decision-making Behavior During Inhalation of 
Subanaesthetic Concentrations of Enflurane. British Journal of Anaesthesia, 50 (12), 1 173-1 178. 

Bentin, S., Collins, G., & Adam, N. (1978). Effects of Low Concentrations of Enflurane on 
Probability Learning. British Journal of Anaesthesia, 50 (12), 1 179-1 183. 

Bhangar, S., Cowlin, S., Singer, B., Sextro, R., & Nazaroff, W. (2008). Ozone Levels in 
Passenger Cabins of Commercial Aircraft on North American and Transoceanic Routes. 
Environmental Science & Technology, 42 (1 1), 3938-3943. 

Bigum, R. (2001, June 22). F-22 Life Support Equipment (LSE). Memorandum from ACC 
Director of Requirements to Aeronautical Systems Center/YF. Document provided to the AOG 
Study Panel of the AF SAB. 

Biasing, T. (2011). Recent Greenhouse Gas Concentrations. Oak Ridge National Laboratory, 
Carbon Dioxide Information Analysis Center. [On-line]. Available: 

http ://cdiac . esd.ornl.gov/pns/ current_ghg.html 

Bobb, A., & Still, K. (2003). Known Harmful Effects of Constituents of Jet Oil Cabin Smoke 
(TOXDET-03-04). Wright-Patterson AFB, OH: Naval Health Center Research Detachment 
(Toxicology). 

Boeing Company. (2002). F-22 Failure Mode and Effects Analysis for the OBOGS. Seattle, 
WA: Author. Document provided to the AOG Study Panel of the AF SAB. 

Boeing Company. (2002). F-22 Failure Mode and Effects Analysis for the Oxygen Monitor 
Controller. Seattle, WA: Author. Document provided to the AOG Study Panel of the AF SAB. 

Boeing, Inc. (201 1). Boeing Toxicology Gap Analysis Spreadsheet. Data provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished. 

Boeing, Inc. (2011). G-Suit Connection. Presented to the AOG Study Panel of the AF SAB 
during fact-finding meeting at Crystal City, VA. Unpublished. (Note: Embedded file from 
Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: Keen document is For 
Official Use Only, Boeing document is Boeing Proprietary)). 

Boeing, Inc. (2011, September). PulseOx Data Aircraft 4164 (September 26, 2011 14:21:44). 
Unpublished data provided to the AOG Study Panel of the AF SAB during fact-finding meeting 
at Crystal City, VA. (Note: Data is proprietary and export controlled). 



199 



Boeing, Inc. (2011, September). PulseOx Data Aircraft 4094 (September 23, 2011 19:26:26). 
Unpublished data provided to the AOG Study Panel of the AF SAB during fact-finding meeting 
at Crystal City, VA. (Note: Data is proprietary and export controlled). 

Boeing, Inc. (2011, October). Pulse Oximeter Data Offset Aircraft 4060 (October 20, 2011 
13:14:38). Unpublished data provided to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. (Note: Data is proprietary and export controlled). 

Boeing, Inc. (2011, October). Pulse Oximeter Data Offset Aircraft 4172 (October 20, 2011 
12:56:50). Unpublished data provided to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. (Note: Data is proprietary and export controlled). 

Boeing, Inc. (2011, November). -107 Team Update (A/C 4022 Tyndall, A/C 4172 (Langley), 
A/C 4060 (Langley)). Briefing presented to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. (Note: Briefing slides are Proprietary). 

Boeing, Inc. (2011, November). On Board Oxygen Generating System (OBOGS). Briefing 
presented to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Note: Briefing slides are Proprietary). 

Boeing, Inc. (2011, November). Aircraft 4165 - November 15, 2011 14:40:12. Briefing slides 
presented to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Note: Briefing slides are Proprietary). 

Boeing, Inc. (n.d.). B-1B Compartment Pressurization Schematic Diagram (Sheet 1 of 6). 
Document extract (Figure 8-2, Technical Order 1B-1B-2-21GS-00-1) provided to the AOG 
Study Panel of the AF SAB. 

Boeing, Inc. (n.d.). B-1B Oxygen System Block Diagram. Document extract (Figure 1, 
Technical Order 1B-1B-2-35GS-00-1) provided to the AOG Study Panel of the AF SAB. 

Boeing, Inc. (n.d.). F-15E Radar Modernization Program Environment Control System 
Schematic Extract (Drawing No. 68J835002, Sheet 15, Revision J, Zones 463-495). Saint Louis, 
MO: Author. (Note: Document is Boeing Proprietary). 

Boeing, Inc. (n.d.). Molecular Characterization Matrix (MCM) 2011 Debrief (Revision 
December 12, 2011). Briefing presented to the AOG Study Panel of the AF SAB during fact- 
finding meeting at Crystal City, VA. (Note: Document is Boeing and Lockheed-Martin 
Proprietary). 

Boeing, Inc. (n.d.). Technical Order 1B-1B-1 (Extract). Document extract (Oxygen System 
Description and Schematic, pages 1-39 through 1-41) provided to the AOG Study Panel of the 
AF SAB. 

Boeing, Inc. (n.d.). Technical Order IB- IB- 1-1 (Extract). Document extract (Emergency 
Oxygen Bottle Duration, Pages 3-95 through 3-100) provided to the AOG Study Panel of the AF 
SAB. 

Boeing, Inc., & Lockheed Martin, Inc. (2011, July). Aircraft Contaminant Testing. Briefing 
slides provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal 
City, VA. (Notes: Slides are Proprietary, Embedded file from Bowerman, Root Cause 
Corrective Action Team Efforts (Note: Bowerman document is Proprietary)). 



200 



Boeing, Inc., & Lockheed Martin, Inc. (2011, July). Carbon Monoxide (CO) Test Data. 
Briefing slides provided to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Crystal City, VA. (Notes: Slides are Proprietary, Embedded file from Bowerman, Root Cause 
Corrective Action Team Efforts (Note: Bowerman document is Proprietary)). 

Boeing, Inc., & Lockheed Martin, Inc. (2011, July). Climb Rate Testing. Briefing slides 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Notes: Slides are Proprietary, Embedded file from Bowerman, Root Cause Corrective 
Action Team Efforts (Note: Bowerman document is Proprietary)). 

Boeing, Inc., & Lockheed Martin, Inc. (2011, July). F-22 OBOGS Challenge Testing Review. 
(2011, July). Briefing presented to the AOG Study Panel of the AF SAB during fact-finding 
meeting at Crystal City, VA. (Note: Briefing is Boeing and Lockheed Martin Proprietary). 

Boeing, Inc., & Lockheed Martin, Inc. (2011, July). Insufficient 02 Content Potential 
Investigation. Briefing slides provided to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. (Notes: Slides are Proprietary). 

Boeing, Inc., & Lockheed Martin, Inc. (201 1, July). NAVAIR Carbon Monoxide (CO) Transient 
Test Data. Briefing slides provided to the AOG Study Panel of the AF SAB during fact-finding 
meeting at Crystal City, VA. (Notes: Slides are Proprietary, Embedded file from Bowerman, 
Root Cause Corrective Action Team Efforts (Note: Bowerman document is Proprietary)). 

Boeing, Inc., & Lockheed Martin, Inc. (2012, January). OBOGS SN284 Challenge Test. Slides 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Note: Slides are proprietary). 

Boeing Military Airplanes Company. (2000, March). Qualification Test Report for Man-Rating 
and Thermal Tests (Brooks AFB, TX) (5PHYCO20). Seattle, WA: Author. Document provided 
to the AOG Study Panel of the AF SAB. (Note: Document is For Official Use Only, 
Copyrighted, and Export Controlled). 

Bomar, J. (1995). Modeling PBA Gas Dynamics. In Pilmanis, A. & Sears, W. (Eds.), Raising 
the Operational Ceiling: Proceedings of a Workshop held At Armstrong Laboratory, Brooks AF 
Base, Texas 13-15 June 1995 (pp. 259-267). Brooks AFB, TX: Armstrong Laboratory. 

Bomar, J., Scott, M., & Smith, D. (1994). Modeling Respiratory Gas Dynamics in the Aviator's 
Breathing System (AL/CF-TR- 1994-0047- Vol. 1). Brooks AFB, TX: Armstrong Laboratory. 

Bowerman, M. (2011, July). F-22 Raptor Life Support System Overview. (2011, July). 
Briefing presented to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Wright-Patterson AFB, OH. Unpublished. (Note: Briefing slides are Boeing proprietary). 

Bowerman, M. (2011). Life Support System Proposed Test Plan. Presented to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished. (Note: 
Embedded file from Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: Keen 
document is For Official Use Only)). 

Bowerman, M. (2012, January). OBOGS Bay Pressure, Ventilation, and Contamination Topics. 
Briefing presented to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Crystal City, VA. (Note: Briefing slides are proprietary). 



201 



Bowerman, M., Arcusa, L., Brown, S., & Happ, R. (2011, July). Root Cause Corrective Action 
Team Efforts. Briefing presented to the AOG Study Panel of the AF SAB during fact-finding 
meeting at Crystal City, VA. (Note: Briefing is Boeing and Lockheed Martin Proprietary and 
contains additional embedded files). 

Bowerman, M., Brown, S., & Happ, R. (2012, January). SAB Hypothesis Update. Briefing 
presented to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Note: Briefing is Boeing and Lockheed Martin Proprietary). 

Bowerman, M., & Happ, R. (2011, December). RCCA Status. Briefing presented to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: Briefing is 
Boeing and Lockheed Martin Proprietary and contains additional embedded files). 

Bowerman, M. (n.d.). Insufficient 02 Content Potential Investigation Findings. Briefing slides 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Notes: Slides are Proprietary, Embedded file from Bowerman, Root Cause Corrective 
Action Team Efforts (Note: Bowerman document is Proprietary)). 

Breed, P. (2011, November). HQ ACC/SG Bioenvironmental Engineering. Briefing presented 
to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Budinger, G., & Mutlu, G. (2011). Pulmonary, Sleep, and Critical Care Updates: Update in 
Environmental and Occupational Medicine 2010. American Journal of Respiratory Critical Care 
Medicine, 183, 1614-1619. * 

Burdon, J., & Glanville, A. (2005). Lung Injury Following Hydrocarbon Inhalation in BAe 146 
Aircrew. Journal of Occupational Health and Safety — Australia, New Zealand, 21 (5), 450-454. 

Burm, A. (2003). Occupational Hazards of Inhalational Anaesthetics. Best Practice & Research 
Clinical Anaesthesiology, 17 (1), 147-161. 

Busch, M. (1992). Trade Study: Life Support Systems / Pilot Breathing Systems. 
Lockheed-Boeing-General Dynamics briefing slides provided to the AOG Study Panel of the AF 
SAB. 

Bush, T. (2002, June 18). Memorandum to ASC/YTJV: Risk to USAF Aircraft (with 
attachments). Document (memorandum and attachments) provided to the AOG Study Panel of 
the AF SAB. (Note: Document is For Official Use only). 

Bush, T. (2011, July). Aircraft Life Support Systems Technical Review Brief to Scientific 
Advisory Board Quick Look Study on Aircraft Oxygen. Briefing presented to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Wright-Patterson AFB, OH. 

Bush, T. (201 1, July). OBOGS Compare Update. Data provided to the AOG Study Panel of the 
AF SAB during fact-finding meeting at Wright-Patterson AFB, OH. 

Butera, S. (2002, April). ECS Schematic with 184 ECS Pack Growth AESA Configuration 
(F-18). Document (schematic) provided to the AOG Study Panel of the AF SAB. 

Cabral, J. (2010). Can We Use Indoor Fungi as Bioindicators of Indoor Air Quality? Historical 
Perspectives and Open Questions. Science of the Total Environment 408 (20), 4285-4295. 

Cain, J., & Fletcher, R. (2010). Diagnosing Metal Fume Fever — An Integrated Approach. 
Occupational Medicine, 60, 398-400. 



202 



Carletti, E., Schopfer, L., Colletier, J., Froment, M., Nachon, F., Weik, M., Lockridge, O., & 
Masson, P. (2011). Reaction of Cresyl Saligenin Phosphate, the Organophosphorus Agent 
Implicated in Aerotoxic Syndrome, with Human Cholinesterases: Mechanistic Studies 
Employing Kinetics, Mass Spectrometry, and X-ray Structure Analysis. Chemical Research in 
Toxicology, 24 (6), 797-808. 

Carpenter, H., Jenden, D., Shulman, N., & Tureman, J. (1959). Toxicology of a Triaryl 
Phosphate Oil. AMA Archives of Industrial Health, 20, 62/234-252. 

Carr, L. (2007, January). Human Systems Integration (Success Cases). Briefing provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Carr, L. (2008, July). Defense Safety Oversight Council and Human Systems Integration. 
Position paper provided to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Crystal City, VA. 

Carr, L. (2009, June). White Paper for HSI Evolution. Paper provided to the AOG Study Panel 
of the AF SAB during fact-finding meeting at Crystal City, VA. 

Carr, L. (2010, August). F-22 HSI Case Study. Briefing provided to the AOG Study Panel of 
the AF SAB during fact-finding meeting at Crystal City, VA. 

Carr, L. (2011, March). HSI implementation Checklist. Document provided to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Carr, L. (2011, July). Air Force HSI Overview SAB Update. Briefing provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Carr, L. (201 1, July). White Paper for HSI Evolution. Paper provided to the AOG Study Panel 
of the AF SAB during fact-finding meeting at Crystal City, VA. 

Carr, L. (n.d.). F-22 Human Systems Integration Case Study (Draft). Paper provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Carr, L. (n.d.). LANTIRN Case Study: Human Systems Integration. Briefing provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Carr, L. (n.d.). Ten Plus Things for HSI Success. Document provided to the AOG Study Panel 
of the AF SAB during fact-finding meeting at Crystal City, VA. 

Carr, L., & Greene, F. (2009, August). Human Systems Integration (HSI) in Acquisition 
(Acquisition Phase Guide) (AFHSIO-004). Falls Church, VA: Air Force Human Systems 
Integration Office. Document provided to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. 

Carr, L., & Greene, F. (2009, August). Human Systems Integration (HSI) in Acquisition 
(Management Guide) (AFHSIO-003). Falls Church, VA: Air Force Human Systems Integration 
Office. Document provided to the AOG Study Panel of the AF SAB during fact-finding meeting 
at Crystal City, VA. 

Carr, L., & Lindberg, R. (2005). Human-System Integration in Air Force Weapon Systems 
Development and Acquisition: Recommendation Implementation. Briefing provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 



203 



Carr, L., & Lindberg, R. (2005). Position Paper: Implementing Human Systems Integration in 
AFMC. Document provided to the AOG Study Panel of the AF SAB during fact-finding 
meeting at Crystal City, VA. 

Chait, R. (2009). Perspectives from Former Executives of the POD Corporate Research 
Laboratories. Washington, DC: National Defense University, Center for Technology and 
Security Policy. 

Chapman, D. (2000). Incapacitation Procedures. In Safety Regulation Group, Flight Operations 
Department Communication #17/2000 (pp. 3-4). Gatwick West Sussex, UK: Civil Aviation 
Authority, Flight Operations Department. 

Chapman, D. (2001). Oxygen Masks. In Safety Regulation Group, Flight Operations 
Department Communication #14/2001 (pp. 1-2) . Gatwick West Sussex, UK: Civil Aviation 
Authority, Flight Operations Department. 

Chapman, D. (2002). UK Public Transport Smoke/Fumes Occurrences. In Safety Regulation 
Group, Flight Operations Department Communication #21/2002 (pp. 1-3) . Gatwick West 
Sussex, UK: Civil Aviation Authority, Flight Operations Department. 

ChevronPhillips Chemical Company. (2011, May). Material Safety Data Sheet: Synfluid PAO 7 
cSt. Document provided to the AOG Study Panel of the AF SAB. 

Committee on Toxicity of Chemicals in Food. (2007). Statement on the Review of the Cabin Air 
Environment, 111 Health in Aircraft Crews and the Possible Relationship to Smoke/Fume Events 
in Aircraft [Online]. Available: http://www.advisorybodies.doh.gov.uk/cotnonfood/index.htm 

Connolly, D., Lee, V., & D'Oyly, T. (2010). Decompression Sickness Risk at 6553m Breathing 
Two Gas Mixtures. Aviation, Space, and Environmental Medicine, 81 (12), 1069-1077. 

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of Cellular Physiology, 36 (1), 115-127. 

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Mixtures to Altitude Decompression Sickness. Aviation, Space, and Environmental Medicine, 
51 (6), 537-541. 

Cooper, C. (201 1, November). Hypoxia - A Multifaceted Threat?. Approach, 56 (6), 9-10. 

Cope, K., Merritt, W., Krenzischek, D., Schaefer, J., Bukowski, J., Foster, W.M., Bernacki, E., 
Dorman, T., Risby, T. (2002). Phase II Collaborative Pilot Study: Preliminary Analysis of 
Central Neural Effects from Exposure to Volatile Anesthetics in the PACU. Journal of 
PeriAnesthesia Nursing, 17 (4), 240-250. 

Countryman, R. (2011, September). BOS Study. Briefing provided to the AOG Study Panel of 
the AF SAB. (Note: Briefing is proprietary). 

Cox, F., & Peterson, G. (2011, December). C2A1 Filter Overview. Briefing presented to the 
AOG Study Panel of the AF SAB. (Note: Briefing is For Official Use Only). 

Coxon, L. (2002). Neuropsychological Assessment of a Group of BAe 146 Aircraft Crew 
Members Exposed to Jet Engine Oil Emissions. Journal of Occupational Health and Safety - 
Australia, New Zealand, 18 (4), 313-319. 



204 



Craig, P., & Barth, M. (1999). Evaluation of the Hazards of Industrial Exposure to Tricresyl 
Phosphate: A Review and Interpretation of the Literature. Journal of Toxicology and 
Environmental Health, Part B, 2 (4), 281-300. 

Crawford, W., & Wells, H. (1973). A Unique Method for Monitoring Cabin Air Pollution from 
Engine Oil in the EB-57D Aircraft (AFML-TR-72-244). Wright-Patterson Air Force Base, OH: 
Air Force Materials Laboratory. 

Crump, D., Harrison, P., & Walton, C. (2011). Aircraft Cabin Air Sampling Study (Parts 1 and 
2). Cranfield, UK: Cranfield University, Institute of Environmental Health. 

Delorey, D. (2010). Hypoxia - A Physiological Threat. Approach 56 (4), 3-5. 

Daniels, M. (2003). Circular Number A-76 (Revised): Performance of Commercial Activities. 
Washington, DC: Office of Management and Budget. 

Daubert, G., Spiller, H., Crouch, B., Seifert, S., Simone, K., & Smolinske, S. (2009). Pulmonary 
Toxicity Following Exposure to Waterproofing Grout Sealer. Journal of Medical Toxicology, 5 
(3), 125-129. 

Daughtrey, W., Biles, R., Jortner B., & Erich, M. (1996). Subchronic Delayed Neurotoxicity 
Evaluation of Jet Engine Lubricants Containing Phosphorus Additives. Fundamental and 
Applied Toxicology, 32 (2), 244-249. 

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Washington, DC: Author. 

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of Carbon Monoxide and Altitude on Aviator Performance: Pathophysiology of Exposure to 
Carbon Monoxide (USAARL Report 78-7). Fort Rucker, AL: United States Army Aeromedical 
Research Laboratory, Aviation Medicine Research Division. 

DeNola, G., Hanhela, P., & Mazurek, W. (2011). Determination of Tricresyl Phosphate Air 
Contamination in Aircraft. Annals of Occupational Hygiene, 55 (7), 710-722. 

DeNola, G., Kibby, J., & Maurek, W. (2008). Determination of Ortho-Cresyl Phosphate Isomers 
of Tricresyl Phosphate Used in Aircraft Turbine Engine Oils by Gas Chromatography and Mass 
Spectrometry. Journal of Chromatography A, 1200 (2), 211-216. 

Dickinson, R., & Franks, N. (2010). Bench-to-Bedside Review: Molecular Pharmacology and 
Clinical Use of Inert Gases in Anesthesia and Neuroprotection. Critical Care, 14 (4), 229-241. 

Diesel, D., O'Connor, R., Nunneley, S., & Morgan, T. (n.d.). Human Performance Testing of 
the F-22 Life Support System. Brooks AFB, TX: Air Force Research Laboratory, Human 
Effectiveness Directorate. Document provided to the AOG Study Panel of the AF SAB. 

Dietzel, K. (2002). Analytical Characterization of Jet Propellant 8 (JP-8) Using Gas 
Chromatography/Mass Spectrometry (GC/MS). Unpublished Masters Thesis. University of 
Georgia. Athens, GA. 

Dodson, W. (2011, July). F-22 Response Checklist: For Operational Bases. Briefing provided 
to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 
Unpublished. 



205 



Drawbaugh, R. (2007, March). Air Force Human Systems Integration: A Report Provided to 
The Joint HSI Steering Group. Washington, DC: Office of the Vice Chief of Staff. Document 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. 

Dreyfus, E., Tramoni, E., & Lehucher-Michel, M. (2008). Persistent Cognitive Functioning 
Deficits in Operating Rooms: Two Cases. International Archives of Occupational and 
Environmental Health, 82 (1), 125-130. 

Drown, D. (2011, June 29). Bullet Background Paper on Status of F-22 Environmental Control 
System Flight Test. Document provided to the AOG Study Panel of the AF SAB. 

Dussault, J. (2004, April). AFRL/IF Presentation for AF SAB Human-System Integration 
"Quick-Look" Study. Briefing slides provided to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. 

Ebersole, C. (2011, July). F-35 Life Support System Overview. Briefing presented to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished. 
(Note: Briefing slides are For Official Use Only). 

Edwards, B. (2011, November). HQ ACC/SG Medical Overview F-22 Return To Fly. Briefing 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. 

Ehrhard, T. (2011, July). F-22 SAB AOG Working Hypotheses. Paper provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Eller, B. (n.d.). HPT Architecture Training. Briefing provided to the AOG Study Panel of the 
AF SAB during fact-finding meeting at Crystal City, VA. 

Environmental Protection Agency, Office of Solid Waste and Emergency Response. (2011, 
June). Background Indoor Air Concentrations of Volatile Organic Compounds in North 
American Residences (1990-2005): A Compilation of Statistics for Assessing Vapor Intrusion 
(EPA530-R-10-001). Washington, DC: Author. 

Erickson, J. (2004, October). Memorandum to AF/CC: HSI Study Update on AF/CC-Directed 
Briefings. Document provided to the AOG Study Panel of the AF SAB during fact-finding 
meeting at Crystal City, VA. 

Erickson, J., & Zacharias, G. (2004). Report on Human-System Integration in Air Force 
Weapon Systems Development and Acquisition (SAB-TR-04-04). Washington, DC: USAF 
Scientific Advisory Board. (Note: Document is For Official Use Only). 

Erickson, J., & Zacharias, G. (2004, August). Human System Integration in Air Force Weapon 
System Development and Acquisition. Washington, DC: USAF Scientific Advisory Board. 
Study outbriefmg provided to the AOG Study Panel of the AF SAB during fact-finding meeting 
at Crystal City, VA. 

Ernsting, J. (1996). Conventional Aircraft Oxygen Systems. In J. Ernsting, & R. Miller (Eds.), 
Advanced Oxygen Systems for Aircraft (AGARDOGRAPH No. 286) (pp. 4-11). Neuilly-Sur- 
Seine, France: Advisory Group for Aerospace Research & Development, North Atlantic Treaty 
Organization. 



206 



Ernsting, J. (2005, August 11). F/A-22 OBOGS Performance on Rapid Decompression. 
Document provided to the AOG Study Panel of the AF SAB. Unpublished letter. 

Ernsting, J., & Miller, R. (1996). Advanced Oxygen Systems for Aircraft (AGARDOGRAPH 
No. 286). Neuilly-Sur-Seine, France: Advisory Group for Aerospace Research & Development, 
North Atlantic Treaty Organization. 

European Committee for Standardization. (2009). Aerospace Series - Aircraft Internal Air 
Quality Standards, Criteria and Determination Methods (BS EN 4618:2009). Brussels: Author. 

ExxonMobil Chemical. (2010, September). Product Safety Summary: Spectrasyn 2 
Polyalphaolefm (PAO) Fluid. Document provided to the AOG Study Panel of the AF SAB. 
(Note: Document is copyrighted). 

Ezzeddine, M. (2011). From Xenon to Argon: A More Clinically Accessible Neuroprotectant? 
Critical Care Medicine, 39 (6), 1589-1590. 

F-22 Combined Test Force, (n.d.). ECS Testing of 2 CAF Jets: Options and Recommendations. 
Briefing provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal 
City, VA (December 13, 201 1). 

F-22 Combined Test Force, (n.d.). F-22 SAB Request for Information. Briefing provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA (December 
13,2011). 

F-22 Combined Test Force, (n.d.). Holloman 23, 27 Sep 2011 Desaturation Investigation. 
Briefing provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal 
City, VA (October 18, 201 1). 

Federal Aviation Administration. (1980, October). Transport Category Airplanes Cabin Ozone 
Concentrations (FAA Advisory Circular #120-38). Washington, DC: Author. 

Fisher, J. (2006). Development of a PBPK Model for JP-8 (AFRL-SR-TR-06-0487). 
Washington, DC: Air Force Office of Scientific Research. 

Flottman, J. (2011, August). Molecular Characterization. Briefing provided to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: Briefing is For 
Official Use Only and is Safety Privileged). 

Fowler, B., & Ackles, K. (1972). Narcotic Effects in Man of Breathing 80-20 Argon-Oxygen 
and Air under Hyperbaric Conditions. Aerospace Medicine, 43 (11), 1219-1224. 

Freudenthal, R., Rausch, L., Gerhart, J., Barth, M., MacKerer, C, & Bisinger, E. (1993). 
Subchronic Neurotoxicity of Oil Formulations Containing Either Tricresyl Phosphate or Tri- 
Orthocresyl Phosphate. Journal of the American College of Toxicology, 12 (4), 409-416. 

Friesen, R. (1992). Oxygen Concentrators and the Practice of Anaesthesia. Canadian Journal of 
Anaesthesia, 39 (5), R-80-84. 

Garanzuay, A. (1992, May 12). Minutes of the F-22 Engineering & Manufacturing 
Development System Safety Group Meeting #2 (5PC00191). Document provided to the AOG 
Study Panel of the AF SAB. 

Gardetto, P. (2011, December). F-22 Status of RTF Pulse Ox in other MPS. Briefing provided 
to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 



207 



Gardetto, P. (2011, November). HQ ACC/SG Pulse Oximetry Effort. Briefing provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Gardetto, P. (2011, August). Physiological Analysis of Test Flight Data. Briefing provided to 
the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing is For Official Use Only and is Safety Privileged). 

General Services Administration. (2012). Federal Acquisition Regulation (Extract: 7.300-305 & 
7.500-503). Provided to the AOG Panel of the AF Scientific Advisory Board. 

Glaister, D., & Jobsis-Vander Vliet, F. (1988). A Near-Infrared Spectrophotometric Method of 
Studying Brain O2 Sufficiency in Man During +Gz Acceleration. Aviation, Space & 
Environmental Medicine, 59 (3), 199-207. 

Gong, H., McManus, M., & Linn, W. (1997). Attenuated Response to Repeated Daily Ozone 
Exposures in Asthmatic Subjects. Archives of Environmental Health, 52 (1), 34-41. 

Gordge, D. (2011, March). Transient and Mission Representative Testing of F-22 OBOGS 
Concentrator for Carbon Monoxide Susceptibility. Presented to the AOG Study Panel of the AF 
SAB during fact-finding meeting at Crystal City, VA. Unpublished. (Note: Embedded file from 
Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: Keen document is For 
Official Use Only)). 

Gordge, D. (201 1, July). NAVAIR Carbon Monoxide Monitoring Efforts. Briefing presented to 
the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing is For Official Use Only, Export Controlled, and Proprietary). 

Gordge, D. (2011, July). Situational Summary — Hypoxia in the F/A-18 Hornet. Briefing 
presented to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. Unpublished. (Note: Briefing slides are Export Controlled and For Official Use Only). 

Gordge, D. (201 1). Transient CO Assessment. Briefing provided to the AOG Study Panel of the 
AF SAB during fact-finding meeting at Crystal City, VA. 

Gordge, D. (n.d.). Highlights of F-22 Concentrator Susceptibility Testing. Briefing provided to 
the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing is Export Controlled and For Official Use Only). 

Grano, J., Roberts, A., & Bigley, A. (2001). Determination of the Minimal, Fresh Gas Flow to 
Maintain a Therapeutic Inspired Oxygen Concentration in a Semi-Closed Anesthesia Circle 
System Using an Oxygen Concentrator as the Oxygen Source (NA-2001-01). Fort Sam 
Houston, TX: US Army Medical Department Center and School. 

Great Lakes Chemical Corporation. (2001). International Uniform Chemical Information 
Database Data Set: Isopropylated Triphenyl Phosphate [Online]. Available: http://www.epa.gov/ 
hpv/ pubs/ summaries/isotriph/c 13331tc.htm 

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and Separation for Dry and Moist CO2/N2 Mixtures. Industrial & Engineering Chemistry 
Research, 44 (4), 937-944. 

Hale, M., & Al-Seffar, J. (2008). Preliminary Report on Aerotoxic Syndrome (AS) and the Need 
for Diagnostic Neurophysiological Tests. Journal of the Association of Neurophysiological 
Scientists, 2, 107-118. 



208 



Hanhela, P., Kibby, J., DeNola, G., & Mazurek, W. (2005). Organophosphate and Amine 
Contamination of Cockpit Air in the Hawk, F-lll and C-130 Aircraft (DSTO-RR-0303). 
Victoria, Australia: Defence Science and Technology Organisation. 

Harder, D. (2011, July). APU Exhaust Re-Ingestion Testing Elmendorf AFB. Briefing slides 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Notes: Slides are Proprietary). 

Harding R. (1995). High altitude breathing systems and requirements. In Pilmanis, A., & Sears 
W., (eds.), Raising the Operational Ceiling: A Workshop on the Life Support and Physiological 
Issues on Flight at 60,000 Feet and Above (Publication No. AL/CF-SR- 1995-0021, pp. 67-73). 
Brooks Air Force Base, TX: The Armstrong Laboratory. 

Harrison, R., Murawski, J., McNeely, E., Guerriero, J., & Milton, D. (2009). Exposure to 
Aircraft Bleed Air Contaminants Among Airline Workers: A Guide for Health Care Providers 
[Online]. Available: http://www.ohrca.org/Medicalprotocol03 1909.pdf 

Harrison, W. (2009, March). Request to investigate and determine requirements for bleed air 
contaminant monitoring and solutions to prevent bleed air contamination [Letter to US Federal 
Aviation Administration and European Aviation Safety Agency]. Atlanta, GA: American 
Society of Heating, Refrigerating and Air-Conditioning Engineers. 

Harrison, R., Murawski, J., McNeeley, E., Guerriero, J., & Milton, D. (2007). Management of 
Exposure to Aircraft Bleed- Air Contaminants Among Airline Workers: A Guide for Health Care 
Workers. Document provided to the AOG Study Panel of the AF SAB. 

Hartz, D. (2011, July). Molecular Characterization Overview. Briefing presented to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Wright-Patterson AFB, OH. 
Unpublished. (Note: Briefing slides are Boeing proprietary). 

Havran, J. (2011, December). F-22 SAB Analysis Presentation. Briefing presented to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Hawker Beechcraft Corporation. (2006, January). Flight Manual: USAF/USN Series T-6A 
Aircraft (Air Force TO 1T-6A-1 / Navy (NAVAIR) A1-T6AAA-NFM-100). Wright-Patterson 
AFB, OH: 664 AESS/LG. (Note: Document is For Official Use Only and contains Export 
Controlled Information). 

Holmdahl, M. (1989). System Design Trade Study Report - Crew Protection (DI-S-3606/T). 
Burbank, CA: Lockheed Aeronautical System. Document provided to the AOG Study Panel of 
the AF SAB. (Note: Document is Competition Sensitive). 

Honeywell, Inc. (n.d.). MCM Debrief. Honeywell Data slides provided to the AOG Study Panel 
of the AF SAB during fact-finding meeting at Crystal City, VA (December 13, 2011). (Note: 
Slides are Proprietary). 

Honeywell, Inc. (2007, July). Receipt Acceptance Test Report OBOGS SN 0169 (No. 
3036WRAP). Document provided to the AOG Study Panel of the AF SAB during fact-finding 
meeting at Crystal City, VA. (Note: Test Report is Copyrighted and Proprietary). 

Honeywell International, Inc. (2007, July). Schematic Diagram, V-22, Subfreezing - Baseline 
Environmental Control System (Drawing No. 636854). Document provided to the AOG Study 
Panel of the AF SAB. (Note: Contains proprietary information). 



209 



Honeywell, Inc. (2008, April). Interim Product Investigation Report (No. 2083844). Document 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. 

Honeywell, Inc. (2008, October). Product Investigation Report No. 2081188. Document 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. 

Honeywell, Inc. (2008, October). Product Investigation Report No. 2082798. Document 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. 

Honeywell, Inc. (2009, April). Product Investigation Report No. 2089090. Document provided 
to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 
(Notes: Portions of the Report are Copyrighted and Proprietary). 

Honeywell, Inc. (2009, June). Acceptance Test Report BRAG Valve SN 0115. Document 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Note: Test Report is Copyrighted and Proprietary). 

Honeywell, Inc. (2010, March). Schematic Diagram, F-15-Radar Modernization Program 
(Drawing No. 67D20006 Version 1). Torrance, CA: Author. (Note: Document is Honeywell 
Proprietary). 

Honeywell, Inc. (2010, September). Product Investigation Report (No. 6001348134). Document 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. 

Honeywell, Inc. (2011, July). Investigation into Incident OBOG SN 226. Test data summary 
(unpublished) provided to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Crystal City, VA. (Notes: Summary is Proprietary, Embedded file from Bowerman, Root Cause 
Corrective Action Team Efforts (Note: Bowerman document is Proprietary)). 

Honeywell, Inc. (2011, July). Investigation Test Report: F22 OBOG 3036W000-003 s/n 0060. 
Report provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal 
City, VA. (Notes: Test Report is Copyrighted and Proprietary, Embedded file from Bowerman, 
Root Cause Corrective Action Team Efforts (Note: Bowerman document is Proprietary)). 

Honeywell, Inc. (2011, July). Investigation Test Report: OXYGEN SYSTEM, CRU-104/A 
(Draft). Report provided to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Crystal City, VA. (Notes: Test Report is Copyrighted and Proprietary). 

Honeywell, Inc. (2011). LSS Technical Memorandum (TM 3075). Document provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Document is Copyrighted and Proprietary). 

Honeywell, Inc. (2011). Preliminary Overview of OBOGS & C2A1 Challenge Testing 5/25 
through 6/3/2011 (Pes Plains Test Overview). Test data summary (unpublished) provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Embedded file from Bowerman, Root Cause Corrective Action Team Efforts (Note: Bowerman 
document is Proprietary)). 



210 



Honeywell, Inc. (2011, July). Simulation of Flight Profile from Aircraft 4011 with Reported 
Hypoxia. Slides provided to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Crystal City, VA. 

Honeywell, Inc. (2011). Heat Exchanger Leak Tests from Elmo, Holloman and Tyndall Incident 
Jets. Presented to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal 
City, VA. Unpublished data. (Note: Embedded file from Keen, Hypoxia Root Cause Corrective 
Action (RCCA) Status (Note: Keen document is For Official Use Only)). 

Hoog, S. (2011, July). SAFETY INVESTIGATION BOARD, OBOGS & Aircrew Flight 
Equipment, F-22 Focus, Incidents. Briefing presented to the AOG Study Panel of the AF SAB 
during fact-finding meeting at Wright-Patterson AFB, OH. (Note: Briefing slides are For 
Official Use Only and Safety Privileged). 

Hoog, S. (2011, July). SAFETY INVESTIGATION BOARD OBOGS & Aircrew Flight 
Equipment to SAB Quick Look Study on Aircraft Oxygen Generation. Briefing presented to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Wright-Patterson AFB, OH. 
(Note: Briefing slides are For Official Use Only and Safety Privileged). 

Horch, T., Miller, R., Bomar, J., Tedor, J., Holden, R., Ikels, K., & Lozano, P. (1983). The F-16 
Onboard Oxygen Generating System: Performance Evaluation and Man Rating 
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Horrigan, D., Wells, C, Guest, M., Hart, G., & Goodpasture, J. (1979). Tissue Gas and Blood 
Analyses of Human Subjects Breathing 80% Argon and 20% Oxygen. Aviation, Space, and 
Environmental Medicine, 50 (4), 357-362. 

Howland, R. (2011, August). AF/SE Class E SIB Rapid Decompression. Briefing presented to 
the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing is For Official Use Only and is Safety Privileged). 

Human Systems Integration Task Force. (2010). Proceedings of the Strategic Frameworks for 
Human Performance and Human Systems Integration. Arlington, TX: University of Texas 
Human Performance Institute. Document provided to the AOG Study Panel of the AF SAB 
during fact-finding meeting at Crystal City, VA. 

Huntsman, M. (201 1, November). Time for the Chamber. Approach, 56 (6), 11-13. 

Ikels, K. (1996). Effects of Contaminants on Molecular Sieve Oxygen Generators. In J. 
Ernsting, & R. Miller (Eds.), Advanced Oxygen Systems for Aircraft (AGARDOGRAPH No. 
286) (pp. 90-94). Neuilly-Sur-Seine, France: Advisory Group for Aerospace Research & 
Development, North Atlantic Treaty Organization. 

Ikels, K., & Adams, J. (1979). Molecular Sieve Oxygen Generating System: The Argon 
Question - A Brief Review. Aviation, Space and Environmental Medicine, 50 (9), 939-942. 

Ikels, K., & Miller, G. (1996). Molecular Sieves, Pressure Swing Absorption, and Oxygen 
Concentrators. In J. Ernsting, & R. Miller (Eds.), Advanced Oxygen Systems for Aircraft 
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Aerospace Research & Development, North Atlantic Treaty Organization. 



211 



Inlet LO Material Changes. (2012, January). Briefing slides presented to the AOG Study Panel 
of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: Briefing slides are 
proprietary). 

Jacques, D. (2010, May). Human Systems Integration in Early Acquisition: A Historical 
Example. Briefing provided to the AOG Study Panel of the AF SAB during fact-finding meeting 
at Crystal City, VA. 

Jamal, G., Hansen, S., & Julu, P. (2002). Low Level Exposures to Organophosphorus Esters 
May Cause Neurotoxicity. Toxicology, 181-182, 23-33. 

Javorsek, D., Howland, R., Hogle, R., & Curtis, A. (2011, July). F-22 All Weather Fighter: 
Recent ECS Testing Results. 22 nd Society of Flight Test Engineers European Community 
Annual Symposium, Tolouse, France. 

Johnson, D., Thompson, D., Clinkenbeard, R., & Redus, J. (2008). Professional Judgment and 
the Interpretation of Viable Mold Air Sampling Data. Journal of Occupational and 
Environmental Hygiene, 5 (10), 656-663. 

Joint Human System Integration Steering Group. (2006, November). Human Systems 
Integration (HSI): Research and Analysis Requirements. Briefing provided to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Jordan, B., & Wright, E. (2010). Xenon as an Anesthetic Agent. AANA Journal 78 (5), 
387-392. 

Kadish, R. (2005, December). Executive Summary: Defense Acquisition Performance 
Assessment. Washington, DC: Office of the Deputy Secretary of Defense, Defense Acquisition 
Performance Project. Document provided to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. 

Keen, A. (201 1, July). F-22 RCCA Fault Tree. Spreadsheet presented to the AOG Study Panel 
of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished. (Note: 
Embedded file from Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: Keen 
document is For Official Use Only). 

Keen, A. (2011, June). Hypoxia RCCA Status. Briefing provided to the AOG Study Panel of 
the AF SAB during fact-finding meeting at Wright-Patterson AFB, OH. Unpublished. (Note: 
Briefing slides are For Official Use Only). 

Keen, A. (2011, July). Hypoxia Root Cause Corrective Action (RCCA) Status. Briefing 
presented to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Note: Briefing slides are For Official Use Only). 

Keen, A. (2011, November). F-22 Emergency Oxygen System Handle. Briefing presented to 
the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing slides are For Official Use Only and Proprietary). 

Keen, A. (201 1, November). 02 Sensor. Briefing presented to the AOG Study Panel of the AF 
SAB during fact-finding meeting at Crystal City, VA. (Note: Briefing slides are For Official 
Use Only and Proprietary). 



212 



Kelso, A., Charlesworth, J., & McVea, G. (1988). Contamination of Environmental Control 
Systems in Hercules Aircraft (Materials Research Laboratory Report MRL-R-1 1 16). Melbourne, 
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Kibby, J., DeNola, G., Hanhela, P., & Mazurek, W. (2005, April). Engine Bleed Air 
Contamination in Military Aircraft. In C. Winder (ed.), Contaminated Air Protection Conference 
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Kim, C, Alexis, N., Rappold, A., Kehrl, H., Hazucha, M., Lay, J., Schmitt, M., Case, M., 
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in Healthy Young Adults Exposed to 0.06 ppm Ozone for 6.6 Hours. American Journal of 
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Kitzes, G. (1956, February). Cabin Air Contamination Problems in Jet Aircraft. Aviation 
Medicine, 27 (1), 53-58. 

Kivi, E. (201 1, August). AF/SE Class E SIB. Briefing presented to the AOG Study Panel of the 
AF SAB during fact-finding meeting at Edwards AFB, CA. (Note: Briefing is For Official Use 
Only and is Safety Privileged). 

Kivi, E. (201 1, August). SIB F-22 Return to Flight Recommendations. Briefing presented to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing is For Official Use Only and is Safety Privileged). 

Kobayashi, A. (2000) In-Flight Cerebral Oxygen Status: Continuous Monitoring by 
Near-Infrared Spectroscopy. Aviation, Space, and Environmental Medicine, 71 (2), 177-183. 

Kobayashi, A., Tong, A., & Kikukawa, A. (2001). In-Flight Cerebral Oxygen Status During 
Air-to-Air Combat Maneuvering. Aviation, Space, and Environmental Medicine, 73 (9), 
919-924. 

Kosnett, M. (201 1, August). Key Steps in Causation Analysis for Individual Patients: A Medical 
Toxicology Perspective. Briefing presented to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Edwards AFB, CA. 

Lamb, M., & Routzahn, R. (1978). Environmental Test and Evaluation of a Molecular Sieve 
On-Board Oxygen Generation System (NADC-78 163-60). Warminster, PA: Naval Air 
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Laumbach, R., & Kipen, H. (2005). Bioaerosols and Sick Building Syndrome: Particles, 
Inflammation, and Allergy. Current Opinion in Allergy and Clinical Immunology, 5 (2), 
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Lipscomb, J., Walsh, M., Caldwell, D., & Narayanan, L. (1995). Inhalation Toxicity of Vapor 
Phase Lubricants (AL/OE-TR-1997-0090). Wright-Patterson AFB, OH: Armstrong Laboratory. 

Litton Systems, Inc., Instruments and Life Support Division. (1990, May). Theory of Operation 
for the F-15E Molecular Sieve Oxygen Generating System (OBOGS) (Publication No. 9307). 
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Liyasova, M., Li, B., Schopfer, L.., Nachon, F., Masson, P., Furlong, C, & Lockridge, O. 
(2011). Exposure to Tri-o-cresyl Phosphate Detected in Jet Airplane Passengers. Toxicology 
and Applied Pharmacology, 256 (3), 337-347. 



213 



Lockheed Martin Aeronautical Systems Company. (1994, April 23). F-22A/B Specification 
Change Notice (Proposed) (Air Vehicle System Specification, 5PPAA001A). Document 
provided to the AOG Study Panel of the AF SAB. 

Lockheed Martin Aeronautical Systems Company. (1994, April 23). F-22A/B Specification 
Change Notice (Proposed) (Cockpit System Segment Specification, 5PPAA004A). Document 
provided to the AOG Study Panel of the AF SAB. 

Lockheed Martin Aeronautical Systems Company. (1993, June 10). Letter: Contract 
F33657-91C-0006, F-22 Engineering and Manufacturing Development (EMD) Program, 
Submittal of ECP 0001-14, Deletion of Election Seat Side Arm Control Initiation and Standby 
Oxygen System Requirements, with attachment (ECP 0001-14) (L93V1224). Document 
provided to the AOG Study Panel of the AF SAB. 

Lockheed Martin Aeronautical Systems Company. (2010, September). F-22 Post EMD Safety 
Critical Functions/Safety Significant Items/Safety Critical Items Listing. Marietta, GA: Author. 
Document provided to the AOG Study Panel of the AF SAB. (Note: Briefing is For Official 
Use Only and is Copyrighted). 

Lockheed Martin Aeronautical Systems Company. (2010, November). Production / Sustainment 
/ Modernization System Safety Program Plan. Marietta, GA: Author. Document provided to the 
AOG Study Panel of the AF SAB. (Note: Briefing is For Official Use Only, Export Controlled, 
and is Copyrighted). 

Lockheed Martin, Inc. (2010, December). VSS OBOGS-IVSC Integration Test Summary. 
Provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. 

Lockheed Martin, Inc. (2011, May). Hypoxia Flight Testing Status. Briefing Provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing is Proprietary). 

Lockheed Martin, Inc. (2011, May). Phase 1 Flight Test Altitude Signal. Briefing Provided to 
the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing is Proprietary). 

Lockheed Martin, Inc. (201 1, May). Phase 1 Flight Test P4 Inlet. Briefing Provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: Briefing is 
Proprietary). 

Lockheed Martin, Inc. (2011, May). Phase 1 Flight Test Summary. Briefing Provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing is Proprietary). 

Lockheed Martin, Inc. (2011, August). RTF Mod Flow. Briefing slide provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Edwards AFB, CA. (Note: Briefing is 
Proprietary). 

Lockheed Martin, Inc. (2011, August). Physiological Issue Recommended RTF Plan. Briefing 
provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. (Note: Briefing is Proprietary). 



214 



Lockheed Martin, Inc. (n.d.). Phase II hypoxia Instrumentation Schematic. Schematic provided 
to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Lockheed Martin, Inc. (n.d.). OBOGS Phase 2 Instrumentation (A/C 4009 July 27, 2011 Test). 
Provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. 

Lockheed Martin, Inc., & Boeing, Inc. (2009). Source Control Drawing: Oxygen System, 
Aircraft Molecular Generating F-22 (5VC91701 Rev G). Provided to the AOG Study Panel of 
the AF SAB. (Note: Document is FOUO, Export Controlled, and Copyrighted). 

Lockheed Martin, Inc., & Boeing, Inc. (1998, October 16). F-22 EMD Weapon System and 
Single Air Vehicle Specification (Unclassified Extract, Page 76). Provided to the AOG Study 
Panel of the AF SAB. (Note: Document is FOUO, Export Controlled, and Copyrighted). 

Lockheed Martin, Inc., & Boeing, Inc. (2011, February). F-22 Flight Testing Request Form: 
Flight Phase II Flight Testing for Hypoxia Root Cause Investigation. Presented to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished. 
(Note: Embedded file from Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: 
Keen document is For Official Use Only)). 

Lockheed Martin, Inc., Boeing, Inc, & F-22 System Program Office. (2011). Multifunction 
Valve (MFVVBRAG Under G Test Plan. Presented to the AOG Study Panel of the AF SAB 
during fact-finding meeting at Crystal City, VA. Unpublished. (Note: Embedded file from 
Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: Keen document is For 
Official Use Only)). 

Lockheed Martin, Inc., Boeing, Inc., & Warner Robins Air Logistics Center. (2011). ATAGS 
Hose Disconnect Test Results. Presented to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. Unpublished data. (Note: Embedded file from Keen, 
Hypoxia Root Cause Corrective Action (RCCA) Status (Note: Keen document is For Official 
Use Only)). 

Long, S. (201 1, August). F-22 SAB Statistics Team. Briefing provided to the AOG Study Panel 
of the AF SAB during fact-finding meeting at Edwards AFB, CA. 

Long, S. (2011, August). F-22 SAB Statistics Team Update. Briefing provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Long, S. (201 1, November 14). F-22 SAB Analysis Presentation. Briefing provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Long, S. (2012, January). F-22 SAB Analysis Presentation. Briefing presented to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Loomis, T., & Krop, S. (1955, February). Medical Laboratories Special Report No. 61: Cabin 
Air Contamination in RB-57A Aircraft (CMLRE-ML-52). Edgewood, MD: Army Chemical 
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Lucchini, R., Placidl, D., Toffoletto, F., & Alessio, L. (1996). Neurotoxicity in Operating Room 
Personnel Working with Gaseous and Nongaseous Anesthesia. International Archives of 
Occupational and Environmental Health, 68 (3), 188-192. 



215 



Luckey, J., Grasso, V., & Manuel, K. (2009). Inherently Governmental Functions and 
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Maher, B. (2010 December). Fear in the Dust — Cancer Epidemics in Turkey Could Hold the 
Secret to Staving off a Public Health Disaster in North Dakota. Nature, 468 (7326), 884-885. 

Manatt, S. (1981). Onboard Oxygen Generation Systems. Aviation, Space, and Environmental 
Medicine, 52 (11), 645-653. 

Marchiando, A. (2011, November). F-22 Medical Response. Briefing provided to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Matthews, Z. (201 1, November). Where's the Green Ring?. Approach, 56 (6), 17-19. 

Mattie, D., & Sterner, T. (2011). Past, Present and Emerging Toxicity Issues for Jet Fuel. 
Toxicology and Applied Pharmacology, 254 (2), 127-132. 

Mattie, D. (2011, July). Toxicology Issues - F-22. Briefing provided to the AOG Study Panel 
of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished. (Note: Document 
is For Official Use Only). 

Maybury, M. (2011, June). F-22 On-Board Oxygen Generating Systems (OBOGS): Analysis of 
Competing Hypotheses (ACH). Briefing presented to the AOG Study Panel of the AF SAB 
during fact-finding meeting at Wright-Patterson AFB, OH. Unpublished. (Note: Briefing slides 
are For Official Use Only). 

Mayes, R., & Profenna, L. (2011, September). F-22 Pilot Questionnaire: Preliminary Results. 
Briefing provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal 
City, VA. 

Mayes, R., & Profenna, L. (2012, January). F-22/F-16 Pilot Questionnaire: Preliminary Results. 
Briefing provided to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal 
City, VA. 

McDonnell, W., Stewart, P., & Smith, M. (2010). Prediction of Ozone-Induced Lung Function 
Responses in Humans. Inhalation Toxicology, 22 (2), 160-168. 

McDonnell Douglas, (n.d.). F/A-18 Environmental Control System: Simplified ECS Schematic 
OBOGS. Document (functional diagram) provided to the AOG Study Panel of the AF SAB. 

McDonnell Douglas, (n.d.). Single Place Aircraft OBOGS System Volume Concentrator to 
Console Disconnect. Drawing provided to the AOG Study Panel of the AF SAB. 

McDonnell Douglas, (n.d.). Two Place Aircraft OBOGS System Volume Concentrator to 
Console Disconnect. Drawing provided to the AOG Study Panel of the AF SAB. 

McDonnell, W., Stewart, P., Smith, M., Pan, W., & Pan, J. (1999). Ozone-Induced Respiratory 
Symptoms: Exposure-Response Models and Association with Lung Function. European 
Respiratory Journal, 14 (4), 845-853. 

McGarvey-Buchwalder, D. (1995). F-22 Life Support System for High Altitude Protection. In 
Pilmanis, A., & Sears W., (eds.), Raising the Operational Ceiling: A Workshop on the Life 
Support and Physiological Issues on Flight at 60,000 Feet and Above (Publication No. 
AL/CF-SR-1995-0021) pp. 337-347. Brooks Air Force Base, TX: The Armstrong Laboratory. 



216 



McGrady, M., & Holmdahl, M. (1992, April). LSS OBOGS Standby Oxygen Trade Study 
(L-8935-92-MBM-013). Document provided to the AOG Study Panel of the AF SAB. 

McKee, R., Lammers, J., Muijser, H., Owen, D., & Kulig, B. (2010). Neurobehavioral Effects of 
Acute Exposure to Aromatic Hydrocarbons. International Journal of Toxicology, 29 (3), 
277-290. " " "~ 

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Michaelis Aviation Consulting. 

Military Agency for Standardization. (1986). Physiological Requirements for Aircraft Molecular 
Sieve Oxygen Concentrating Systems (STANAG 3865 2 nd Edition). Brussels, Belgium: Author. 

Miller, G. (1988). Ozone Contaminant Testing of a Molecular Sieve Oxygen Concentrator 
(MSOC). SAFE Journal 18 (4), 26-34. 

Miller, G. (1992). A 99% Purity Molecular Sieve Oxygen Generator. In Technology 2001 
(NASA Publication No. 3136, Volume I), 523-535. 

Miller, G. (2011, July). F-22 OBOGS. Briefing presented to the AOG Study Panel of the AF 
SAB during fact-finding meeting at Crystal City, Arlington, VA. Unpublished. (Note: Briefing 
slides are For Official Use Only). 

Miller, G. (2011, July). F-22 OBOGS: 4009 Flight Data Review. Briefing presented to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. (Note: 
Briefing is For Official Use Only and Proprietary). 

Miller, G. (2011, July). OBOGS Bleed Air Standards. Briefing presented to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, Arlington, VA. 

Miller, G. (201 1, June). F-22 OBOGS Potential Failure Modes. Briefing presented to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Wright-Patterson AFB, OH. 

Miller, G. (2011, December). F-22 OBOGS Bay Pressure Theory. White Paper provided to the 
to the AOG Study Panel of the AF SAB. 

Miller, R., & Ernsting, J. History of Onboard Generation of Oxygen. Ikels, K. (1996). Effects 
of Contaminants on Molecular Sieve Oxygen Generators. In J. Ernsting, & R. Miller (Eds.), 
Advanced Oxygen Systems for Aircraft (AGARDOGRAPH No. 286) (pp. 12-17). 
Neuilly-Sur- Seine, France: Advisory Group for Aerospace Research & Development, North 
Atlantic Treaty Organization. 

Miller, R., Ikels, K., Lamb, M., Boscola, E., & Ferguson, R. (1980). Molecular Sieve Generation 
of Aviator's Oxygen: Performance of a Prototype Under Simulated Flight Conditions. Aviation, 
Space, and Environmental Medicine, 5 1 (7), 665-673. 

Miller, R., Theis, C, Stork, R., & Ikels, K. (1977). Molecular Sieve Generation of Aviator's 
Oxygen: Breathing Gas Composition as a Function of Flow, Inlet Pressure, and Cabin Altitude 
(SAM-TR-77-40). Brooks AFB, TX: USAF School of Aerospace Medicine. 

Miskot, J. (2011, August). Flight Test Data Review: 02 and RAE Data. Briefing presented to 
the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Mitchell, A., & Zuber, M. (2011, July). Orientation and Administration for New AF SAB 
Members and Consultants. Briefing presented to the AOG Study Panel of the AF SAB during 



217 



fact-finding meeting at Wright-Patterson AFB, OH. Unpublished. (Note: Briefing slides are 
For Official Use Only). 

Montgomery, M., Wier, G., Zieve, F., & Anders, M. (1977). Human Intoxication Following 
Inhalation Exposure to Synthetic Jet Lubricating Oil. Clinical Toxicology, 1 1 (4), 423-426. 

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Miller, R. (Ed.), Anesthesia (5 th ed.) (Chapter 67). Philadelphia: Churchill Livingston. 
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040596r00.HTM 

Moore, D. (2011, June). Basic Concepts in Toxicology. Briefing presented to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Edwards AFB, CA. 

Morgan, T. (2011, July). BRAG Valve Overview. Briefing presented to the AOG Study Panel 
of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished. (Note: Briefing 
slides are For Official Use Only, Export Controlled, and Proprietary). 

Munkvold, G., Teague, K., Edgar, T., & Beaman, J. (1992). Prediction of Bed Pressure Profiles 
inOBOGS. Proceedings of the 30 th SAFE Symposium, 58-69. 

Murawski, J. (2005). Occupational and Public Health Risks. In M. Hocking (Ed.), Handbook of 
Environmental Chemistry, Volume 4H (Air Quality in Airplane Cabins and Similar Enclosed 
Spaces) (pp. 25-51). Berlin: Springer. 

Murawski, J. (2011). AFA-CWA Review of Cranfield University, Institute of Environment & 
Health Aircraft Cabin Air Sampling Study (Parts 1 and 2), March- April 201 1. Washington, DC: 
Association of Flight Attendants-CWA. 

Murawski, J. (2011, July). Case Study: Analysis of Reported Contaminated Air Events at One 
Major US Airline in 2009-10 (AIAA 2011-5089). 41 st International Conference on 
Environmental Systems, Portland, OR. 

National Research Council. (2000). Aromatic Phosphate Plasticizers. In Toxicological Risks of 
Selected Flame-Retardant Chemicals (pp. 387-416). Washington, DC: National Academies 
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National Research Council (Committee on Airliner Cabin Air Quality). (2002). The Airliner 
Cabin Environment: Air Quality and Safety. Washington, DC: National Academies Press. 

National Research Council (Committee on Toxicology). (2007). Carbon Dioxide. In Emergency 
and Continuous Exposure Guidance Levels for Submarine Contaminants (pp. 46-66). 
Washington, DC: National Academies Press. 

Naval Air Systems Command (2011, October). F/A-18 and EA-18G Physiological Episodes 
Update with PET #7 Updates). Briefing provided to the AOG Study Panel of the AF SAB 
during fact-finding meeting at Crystal City, VA. (Note: Briefing is For Official Use Only). 

Neubeck, G. (1995). F-22 Concept of Operations above 50,000-ft. In Pilmanis, A., & Sears W., 
(eds.), Raising the Operational Ceiling: A Workshop on the Life Support and Physiological 
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Brooks Air Force Base, TX: The Armstrong Laboratory. 



218 



Nilsson, R., Bjordal, C, Andersson, M., Bjordal, J., Nyberg, A., Welin, B., & Willman, A. 
(2005). Health Risks and Occupational Exposure to Volatile Anaesthetics - A Review with a 
Systematic Approach. Journal of Clinical Nursing, 14 (2), 173-186. 

North Atlantic Treaty Organization Standardization Agency. (2005). Characteristics of Gaseous 
Breathing Oxygen, Liquid Breathing Oxygen and Supply Pressures, Hoses and Replenishment 
Couplings (STANAG 7106 2 nd Edition). Brussels, Belgium: Author. 

North Atlantic Treaty Organization Standardization Agency. (2008). On Board Oxygen 
Generating Systems (OBOGS) Performance Standards (STANAG 7187 GGS 1 st Edition). 
Brussels, Belgium: Author. 

Northrop Grumman Inc. (n.d.). Technical Order 1B-2A-1 (Extract). Document extract (Pages 
1-177 through 1-182) provided to the AOG Study Panel of the AF SAB. 

Northrop Grumman Corporation, (n.d.). Technical Order 1B-2A-2-35GS-00-1. Document 
extract (Section 6.2 - 6.4)) provided to the AOG Study Panel of the AF SAB. 

02 Hardware & Update 3.6 Hardware Summary. (2012, January). Briefing presented to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

O'Connor, R. (1995). Use of Variable Oxygen Concentrations to 50,000 Feet. In Pilmanis, A. 
& Sears, W. (Eds.), Raising the Operational Ceiling: Proceedings of a Workshop held At 
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O'Connor, R., Diesel, D., & Bomar, J. (1996). Effect of Rapid Decompression (RD) to 60,000 
Feet Using 94% Oxygen and Assisted Positive Pressure Breathing (Abstracts of 1996 Annual 
Scientific Meeting, Abstract #249). Aviation, Space, and Environmental Medicine, 67 (7), 705. 

O'Connor, R., & Miller, G. (1997). Altitude Tests of Select Components of the F-22 Life 
Support System Used with Current USAF Flight Equipment. Brooks AFB, TX: Air Force 
Research Laboratory. Document provided to the AOG Study Panel of the AF SAB. 

O'Connor, R. (2000). Combined F-22 and Current USAF Life Support Equipment - Altitude 
Evaluation. Brooks AFB, TX: Air Force Research Laboratory. Document provided to the AOG 
Study Panel of the AF SAB. 

Osburn, J., Stitzell, J., & Peterson, R. (1969). Diffusion of Argon, Krypton, and Xenon in Olive 
Oil. Journal of Applied Physiology, 27 (5), 624-629. 

Paciorek, K., Nakahara, B. & Kratzer, R. (1979). Fluid Contamination of Aircraft-Cabin Air and 
Breathing Oxygen (SAM-TR-79-34). Brooks AFB, TX: USAF School of Aerospace Medicine. 

Pappas, G., Herbert, R., Henderson, W., Koening J., Stover, B., & Barnhart, S. (2000). The 
Respiratory Effects of Volatile Organic Compounds. International Journal of Occupational and 
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219 



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Pratt & Whitney, Inc. (201 1, August). Collapsed Left Side Scavenge Hose. Briefing provided to 
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Pratt & Whitney, Inc. (2012, January). Fl 19-PW-100 Engine Bleed Air Capability Over Service 
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Reynolds, T., Eklund, T., & Haack, G. (2001). Onboard Inert Gas Generation System/Onboard 
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222 



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Spengler, J., Ludwig, S., & Weker, R. (2004). Ozone Exposures During Trans-Continental and 
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Stephens, K., & Wilcher, K. (201 1, July). Final Report of Bleed Air Composition Measurements 
on Fl 19 Engines at Elmendorf AFB, AK. Arnold Air Force Base, TN: Arnold Engineering 
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fact-finding meeting at Crystal City, VA. (Notes: Report is Export Controlled, Embedded file 
from Bowerman, Root Cause Corrective Action Team Efforts (Note: Bowerman document is 
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Stober, E., & Bershitsky. (2011, July). Summary of Zeolite Bed Testing with Aviation Fluid 
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Thomson Reuters (Healthcare) Inc. (n.d.). Argon - HAZARDTEXT© Hazard Management. 
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224 



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meeting at Crystal City, VA. 

Tripp, L., Chelette, T., Savul, S., & Widman, R. (1998). Female Exposure to High G: Effects of 
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United Kingdom Ministry of Defence. (2008). The Human View Handbook for MODAF. 
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United States Air Force. (1992, October). U.S. Air Force Guide Specification, Environmental 
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United States Air Force. (2001, March). Aircraft Information Program (Air Force Handbook 
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United States Air Force. (2005, September). Airworthiness Certification Criteria — Expanded 
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225 



United States Air Force. (2009, February). FY09 Human Systems Integration Management Plan. 
Washington, DC: Office of the Air Force Vice Chief of Staff, Air Force Human Systems 
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fact-finding meeting at Crystal City, VA. 

United States Air Force. (2009, May). Acquisition Improvement Plan. Washington, DC: Office 
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United States Air Force. (201 1). F-22 ECS Shutdown Test Results. Presented to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished. (Note: 
Embedded file from Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: Keen 
document is For Official Use Only)). 

United States Air Force. (2011). Flight Manual F-22A Raptor (TO 1F-22A-1). Hill AFB, UT: 
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United States Air Force. (2011). Nonnuclear Weapons Delivery Flight Manual F-22A Raptor 
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United States Air Force (2011). Test Resource Planning Council (F-22 Division Charter 63-8). 
Wright-Patterson AFB, OH: Aeronautical Systems Center, F-22A Division (ASC/WWU). 

United States Air Force. (201 1, February). [OBOGS Test Results]. Presented to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished raw data. 
(Note: Embedded file from Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: 
Keen document is For Official Use Only)). 

United States Air Force. (2011, February). F-22 Engine Run OBOGS Performance Test 
Procedure (TO-OBOGS-001 Rev C). Wright-Patterson AFB, OH; F-22 System Program Office. 
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United States Air Force. (2011, September 6). Safety Time Compliance Technical Order: 
Inspections in Support of Source - Vulnerability Assessment Matrix, F-22A (Technical Order 
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United States Air Force. (2011, September 16). Safety Time Compliance Technical Order: 
Cockpit Air Quality and On-Board Oxygen Generation System (OBOGS) Performance Test, 
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AOG Study Panel of the AF SAB. 

United States Air Force, (n.d.). SAF/AQ-AFHSIO History Survey (Calendar Year 2010). 
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Crystal City, VA. 

United States Air Force (Aeronautical Systems Center, F-22A Division). (2011). F-22 
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226 



United States Air Force (Aeronautical Systems Center, F-22A Division). (2011, July). F-22 
Safety Critical Function Overview. Briefing provided to the AOG Study Panel of the AF SAB. 
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United States Air Force (Aeronautical Systems Center, F-22A Division). (201 1, July). Return to 
Flight Operations. Briefing presented to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. (Note: Briefing is For Official Use Only). 

United States Air Force (Aeronautical Systems Center, F-22A Division), (n.d.). F-22 OBOGS 
Inlet Pressure Interruption Test - OBOG Pressure Transient Testing Data. Unpublished raw 
data. Data provided to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Crystal City, VA. (Note: Embedded file from Bowerman, Root Cause Corrective Action Team 
Efforts (Note: Bowerman document is Proprietary)). 

United States Air Force (Aeronautical Systems Center, F-22A Division), (n.d.). F-22 Life 
Support System Change List (OBOGS and BRAG Changes). Data spreadsheet provided to the 
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document is Proprietary)). 

United States Air Force Directorate of Studies and Analyses (AF/A9). (2011, November 29). 
F-22 SAB Analysis Presentation. Briefing slides provided to SAA Study Panel of the AF SAB 
at fact finding meeting in Crystal City, Arlington, VA. 

United States Air Force Inspection Agency. (2006). Human Systems Integration (HSI) in Air 
Force Acquisitions (Eagle Look No. 99-501) (Draft). (Note: Document is For Official Use 
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United States Air Force Safety Center. (2011). F-22 Air Test Plan (Elmendorf and Holloman). 
Presented to the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, 
VA. Unpublished. (Note: Embedded file from Keen, Hypoxia Root Cause Corrective Action 
(RCCA) Status (Note: Keen document is For Official Use Only)). 

United States Air Force Safety Center, (n.d.). AFSAS #789775 - Decompression Sickness. 
Briefing slide provided to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Crystal City, VA. Unpublished. 

United States Air Force Safety Center, (n.d.). Contaminants vs Hypoxia (3 Cases: AFSAS 
231395, 797060, 951510). Summary Paper provided to the AOG Study Panel of the AF SAB 
during fact-finding meeting at Crystal City, VA. Unpublished. 

United States Air Force Safety Center. (201 1). Engine Bleed Air Top 10. Presented to the AOG 
Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished data. 
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Keen document is For Official Use Only)). 

United States Air Force Safety Center. (2011). [F-22 Pilot Blood and Breath Samples]. 
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United States Air Force Safety Center. (2011). [OBOGS Inlet Chemicals]. Unpublished raw 
data. 



227 



United States Air Force Safety Center. (2011). [OBOGS Outlet Chemicals]. Unpublished raw 
data. 

United States Air Force Safety Center. (201 1). Swab Test Results. Presented to the AOG Study 
Panel of the AF SAB during fact-finding meeting at Crystal City, VA. Unpublished data. (Note: 
Embedded file from Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: Keen 
document is For Official Use Only). 

United States Air Force School of Aerospace Medicine. (2011). Carbon Monoxide Sampling at 
F-22 Host Bases Report. Wright Patterson AFB, OH: Author. 

United States Air Force School of Aerospace Medicine. (2011). CONSULTATIVE LETTER: 
INITIAL SCREENING OF F-22 RAPTOR FLEET FOR ENVIRONMENTAL 
CONTAMINANTS THAT MAY CAUSE "HYPOXIA-LIKE" SYMPTOMS. Document 
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VA. 

United States Air Force School of Aerospace Medicine. (2011, February). US AF S AM/OEHR 
Sampling Plan for F-22 Fleet at Langley AFB, VA. Presented to the AOG Study Panel of the AF 
SAB during fact-finding meeting at Crystal City, VA. Unpublished. (Note: Embedded file from 
Keen, Hypoxia Root Cause Corrective Action (RCCA) Status (Note: Keen document is For 
Official Use Only)). 

United States Air Force Scientific Advisory Board. (1996). New World Vistas: Air and Space 
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Assessment and Chemical Exposure Guidelines for Deployed Military Personnel (Technical 
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United States Congress. (2005, May). National Defense Authorization Act for Fiscal Year 2006: 
Report of the Committee on Armed Services, House of Representatives on H.R. 1815. 
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the AF SAB during fact-finding meeting at Crystal City, VA. 

United States Congress. (2008, May). Duncan Hunter National Defense Authorization Act for 
Fiscal Year 2009: Report of the Committee on Armed Services of the House of Representatives 
on House Resolution 5658 (Report 110-652, pp. 272-273). Washington, DC: US Government 
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fact-finding meeting at Crystal City, VA. 

United States Department of Defense. (1985). Design and Installation of Liquid Oxygen 
Systems in Aircraft General Specification for (MIL-D-19326G). Lakehurst, NJ: Naval Air 
Engineering Center. 

United States Department of Defense. (1994). Aircrew Station and Passenger Accommodations 
(Mil-Std-1776A (USAF) Appendix A). Wright-Patterson AFB, OH: Aeronautical Systems 
Center. Document provided to the AOG Study Panel of the AF SAB. (Note: Document is For 
Official Use Only). 

United States Department of Defense. (1997). Performance Specification, Lubricating Oil, 
Aircraft Turbine Engine, Synthetic Base, NATO Code Number 0-156 (MIL-PRF-23699F). 
Lakehurst, NJ: Naval Air Warfare Center. 



228 



United States Department of Defense. (1997). Vision 21 : The Plan for 21st Century Laboratories 
and Test and Evaluation Centers of the Department of Defense - Report to the President and 
Congress. Washington, DC: Author. 

United States Department of Defense. (1998). Defense Standardization Program (DSP) (DoD 
Instruction 4120.24, Dated June 18, 1998, Updated March 1, 2000). Washington, DC: Office of 
the Under Secretary of Defense (Acquisition and Technology). 

United States Department of Defense. (1998). Department of Defense Joint Services 
Specification Guide: Crew Systems Oxygen and Breathing Systems Handbook (JSSG-2010-10). 
Wright-Patterson AFB, OH: Aeronautical Systems Center (ASC/ENSI). 

United States Department of Defense. (2000, March). Defense Standardization Program (DSP) 
Policies and Procedures (DoD Manual 4120.24M). Washington, DC: Office of the Under 
Secretary of Defense (Acquisition and Technology). 

United States Department of Defense. (2007, April). DoD Architecture Framework Volume 1 
(Definitions and Guidelines, Version 1.5). Washington, DC: Author. Document provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

United States Department of Defense. (2008). Operation of the Defense Acquisition System 
(DoD Instruction 5000.02). Washington, DC: Office of the Undersecretary of Defense 
(Acquisition, Technology, and Logistics). 

United States Department of Defense Office of the Inspector General. (1994, June). Human 
Systems Requirements for Air Force Acquisition Programs (Report No. 94-124). Arlington, VA: 
Author. Document provided to the AOG Study Panel of the AF SAB during fact-finding 
meeting at Crystal City, VA. 

United States Department of Energy. (2008). Temporary Emergency Exposure Limits for 
Chemicals: Methods and Practice (DOE-HDBK-1046). Washington, DC: Author. 

United States Environmental Protection Agency. (2000). Air Quality Criteria for Carbon 
Monoxide (EPA 600/P-99/001F). Washington, DC: Environment Protection Agency, Office of 
Research and Development. 

United States General Accounting Office. (2003, February). Best Practices: Setting 
Requirements Differently Could Reduce Weapon Systems' Total Ownership Costs (GAO Report 
03-57). Washington, DC: Author. Document provided to the AOG Study Panel of the AF SAB 
during fact-finding meeting at Crystal City, VA. 

United States General Accounting Office. (2003, June). Military Personnel: Navy Actions 
Needed to Optimize Ship Crew Size and Reduce Total Ownership Costs (GAO Report 03-520). 
Washington, DC: Author. Document provided to the AOG Study Panel of the AF SAB during 
fact-finding meeting at Crystal City, VA. 

United States General Accounting Office. (2008, February). Best Practices: Increased Focus on 
Requirements and Oversight Needed to Improve DOD's Acquisition Environment and Weapon 
System Quality (GOA Report 08-294). Washington, DC: Author. Document provided to the 
AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Unknown Author, (n.d.). B-2 OBOGS Diagram (Oxygen System). Document extract (Page 
332) provided to the AOG Study Panel of the AF SAB. 



229 



Unknown Author, (n.d.). F/A-18 OBOGS. Document (functional diagram) provided to the 
AOG Study Panel of the AF SAB. 

Unknown Author, (n.d.). Sealed Back-up Oxygen System B-1B. Document extract (Description 
and Schematic, with Photograph of Installed System) provided to the AOG Study Panel of the 
AF SAB. 

Vadnaise, D. (2011, July). Safety Investigations and the DoD Privilege. Briefing presented to 
the AOG Study Panel of the AF SAB during fact-finding meeting at Wright-Patterson AFB, OH. 

Van Netten, C. (1998). Air Quality and Health Effects Associated with the Operation of BAe 
146-200 Aircraft. Applied Occupational and Environmental Hygiene, 13 (10), 733-739. 

Van Netten, C, & Leung, V. (2000). Comparison of the Constituents of Two Jet Engine 
Lubricating Oils and Their Volatile Pyrolytic Degradation Products. Applied Occupational and 
Environmental Hygiene, 15 (3), 277-283. 

Van Oss, J. (2011, August 26). ASC/WWUK Memorandum to Lockheed Martin Aeronautics 
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Verhein, K., Hazari, M., Moulton, B., Jacoby, I., Jacoby, D., & Fryer, A. (2011). Three Days 
After a Single Exposure to Ozone, the Mechanism of Airway Hyperreactivity is Dependent on 
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Neurotoxicology, 26 (2), 193-198. 

Warr, R., & Chapin, P. (2011, August). Bayesian Analysis and Statistical Approaches. Briefing 
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Weibrecht, K., & Rhyee, S. (2011). Acute Respiratory Distress Associated with Inhaled 
Hydrocarbon. American Journal of Industrial Medicine, 54 (12), 91 1-914. 

West, K., Mayes, R., & Tripp, L. (2011, November). F-22 Physiologic Monitoring & Analysis. 
Briefing presented to the AOG Study Panel of the AF SAB during fact-finding meeting at 
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West, K., Mayes, R., & Tripp, L. (2012, January). F-22 Data Analysis Center. Briefing 
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VA. 

White, C, & Martin, J. (2010). Chlorine Gas Inhalation, Human Clinical Evidence of Toxicity 
and Experience in Animal Models. Proceedings of the American Thoracic Society, 7 (4), 
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230 



Winder, C. (Ed). (2005). Contaminated Air Protection: Proceedings of the Air Safety and Cabin 
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Winder, C, & Balouet, J-C. (2002). The Toxicity of Commercial Jet Oils. Environmental 
Research, 89 (2), 146-164. 

Witkowski, C. (2011, June 23). Military Crewmembers Breathing Toxic Engine Oils. 
Correspondence to Vice Admiral David Architzel, Commander, Naval Air Systems Command. 
Washington, DC: Association of Flight Attendants. 

Wong, K. (1996). Carbon Dioxide. In Subcommittee on Spacecraft Maximum Allowable 
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Humans, Volume 68, Silica; Summary of Data Reported and Evaluation (pp. 307-333). Lyon, 
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Full Public Report: Alkane 1 (File No. NA/254). Camperdown, New South Wales, Australia: 
Author. 

Wyman, D. (2011, December). F-22 Status of RTF C2A1 Filter Analysis. Briefing presented to 
the AOG Study Panel of the AF SAB during fact-finding meeting at Crystal City, VA. 

Young, J. (2008, April 3). Designation of Senior Official to Coordinate and Manage Human 
Systems Integration (HSI) Activities Throughout the Acquisition Programs of the Department of 
Defense (DoD). Letter from Undersecretary of Defense (Acquisition, Technology, and 
Logistics) provided to the AOG Study Panel of the AF SAB during fact-finding meeting at 
Crystal City, VA. 

Znoy, S. (2011, April). CSU-23/P Advanced Technology Anti-Gravity Suit (ATAGS) 
Disconnect Analysis. Presented to the AOG Study Panel of the AF SAB during fact-finding 
meeting at Crystal City, VA. Unpublished. (Note: Embedded file from Keen, Hypoxia Root 
Cause Corrective Action (RCCA) Status (Note: Keen document is For Official Use Only)). 



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Appendix O: Initial Distribution 



Air Force Leadership 

SAF/OS - Secretary of the Air Force 
AF/CC - Chief of Staff of the Air Force 
SAF/US - Under Secretary of the Air Force 
AF/C V - Vice Chief of Staff of the Air Force 

Air Force Secretariat and Staff 

SAF/AQ - Assistant Secretary (Acquisition) 

SAF/CIO A6 - Chief, Information Dominance and Chief Information Officer 
SAF/FM - Assistant Secretary (Financial Management and Comptroller) 
SAF/GC - General Counsel * 

SAF/IE - Assistant Secretary (Installations, Environment, and Logistics) 

S AF/IG - Inspector General 

SAF/LL - Director of Legislative Liaison 

SAF/PA - Director of Public Affairs 

AF/CVA - Assistant Vice Chief of Staff 

AF/JA - The Judge Advocate General 

AF/RE - Chief of the Air Force Reserve 

AF/SB - Military Director of the Scientific Advisory Board 

AF/SE - Chief of Air Force Safety 

AF/SG - Air Force Surgeon General 

AF/ST - Chief Scientist of the Air Force 

AF/TE - Director of Test and Evaluation 

AF/A1 - DCS Manpower, Personnel, and Services 

AF/A2 - DCS Intelligence, Surveillance, and Reconnaissance 

AF/A3/5 - DCS Air Space and Information Operations, Plans and Requirements 

AF/A4/7 - DCS Logistics, Installations, and Mission Support 

AF/A8 - DCS Strategic Plans and Programs 

AF/A9 - Director of Studies and Analyses, Assessments, and Lessons Learned 
AF/A10 - Director of Strategic Deterrence and Nuclear Integration 
NGB/CF - Chief of the Air National Guard 

Air Force Major Commands and Direct Reporting Units 

ACC - Air Combat Command 

AETC - Air Education and Training Command 

AFGSC - AF Global Strike Command 

AFMC - AF Materiel Command 

AFRC - AF Reserve Command 

AFSOC - AF Special Operations Command 

AFSPC - AF Space Command 



233 



AMC - Air Mobility Command 
PACAF - Pacific Air Forces 
USAFE - US Air Forces Europe 
AFPA - Air Force Petroleum Agency 
AFSC - Air Force Safety Center 

Combatant and Regional Commands 

US Central Command 

US European Command 

US Joint Forces Command 

US Northern Command 

US Pacific Command 

US Southern Command 

US Special Operations Command 

US Strategic Command 

US Transportation Command 

Other DoD and Service Advisory Boards 

Army Science Board 

Defense Policy Board 

Defense Science Board 

Naval Research Advisory Committee 

Naval Studies Board 

Executive Office of the President 

National Security Council 

Office of the Secretary of Defense and Defense Agencies 

Under Secretary of Defense (Acquisition, Technology, and Logistics) 
Director of Defense Research and Engineering 
Defense Advanced Research Projects Agency 

Other Military Services 

Assistant Secretary of the Army (Acquisition, Logistics, and Technology) 
Assistant Secretary of the Navy (Research, Development, and Acquisition) 
Naval Air Systems Command 

Joint Chiefs of Staff 

Chairman, Joint Chiefs of Staff 

Vice Chairman, Joint Chiefs of Staff 

Joint Chiefs of Staff, Director of Intelligence (J-2) 

Joint Chiefs of Staff, Director of Operations (J-3) 

Joint Chiefs of Staff, Director of Strategic Plans and Policy (J-5) 

Joint Chiefs of Staff, Director of C4 Systems (J-6) 



234 



Joint Chiefs of Staff, Director of Operational Plans and Joint Force Development (J-7) 
Joint Chiefs of Staff, Director of Force Structure, Resources, and Assessment (J-8) 

Libraries and Data Repositories 

National Defense University Library 

US Military Academy Library 

US Naval Academy Library 

US Air Force Academy Library 

Air University Library 

Air Force Institute of Technology Library 

US Army War College 

US Army Command and General Staff College 

US Naval War College (includes both Naval War College and Navy Staff College) 
USMC Command and Staff College 
Library of Congress 
Pentagon Library 

Defense Technical Information Center 



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REPORT DOCUMENTATION PAGE 


Form Approved 
OMB No. 0704-0188 


Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing 
instructions, searching existing data sources, gathering and manipulating the data needed, and completing and reviewing the collection of 
information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions 
for reducing the burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis 
Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget Paperwork Reduction Project (0704-0188), 
Washington, DC 20503. 


1 . AGENCY USE ONLY (Leave Blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED 

1 February 2012 Final, June 201 1 - January 2012 


4. TITLE AND SUBTITLE 

Aircraft Oxygen Generation 


5. FUNDING NUMBERS 


6. AUTHORS: 

General Gregory Martin, USAF, (ret) (Chair), Lieutenant General George 
Muellner, USAF (ret) (Vice Chair), Major General Joseph Anderson, USMC 
(ret), Mr. James Brinkley, Hon. Dr. Lawrence Delaney, Dr. Peter Demitry, Dr. 
David Moore, General Thomas Moorman, USAF (ret) 


7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

HQ USAF/SB 

1 180 AF PENTAGON RM 5E815 
WASHINGTON, DC 20330-1180 


8. PERFORMING ORGANIZATION 
REPORT NUMBER 

SAB-TR- 11-04 


9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 

SAF/OS, AF/CC 

1670 AIR FORCE PENTAGON 

WASHINGTON, DC 20330-1670 


10. SPONSORING/MONITORING AGENCY 
REPORT NUMBER 


11. SUPPLEMENTARY NOTES 


12a. DISTRIBUTION/ AVAILABILITY STATEMENT 

Approved for Public Release, Distribution Unlimited 


12b. DISTRIBUTION CODE 

A 


13. ABSTRACT 

There have been an increasing number of hypoxia-type incidents, especially in the F-22 Raptor aircraft, that may be 
related to on-board oxygen generating systems (OBOGS). This report details recommendations made by the USAF 
Scientific Advisory Board's Aircraft Oxygen Generation (AOG) Quicklook Study to help mitigate this safety problem. 
The AOG Study Panel received a large number of briefings and perspectives on various aircraft OBOGS standards and 
designs in general; the F-22 and F-22 OBOGS in particular, pilot physiological performance under various conditions, 
and many other related issues, from within and outside the United States Government. The Study Panel evaluated the 
current F-22 oxygen system, OBOGS and life support systems in general (including contaminants that could affect 
OBOGS operation), and human responses to high altitude rapid cabin altitude changes/rapid decompression 
environment with less than 90% oxygen. It also assisted with: F-22 return-to-fly criteria as requested, evaluation of Air 
Standards, review and validation of performance-based acquisition programs and associated risk analysis protocols, and 
with reviewing and revalidating aircrew flight equipment affiliated with OBOGS-equipped aircraft. 


14. SUBJECT TERMS 

Aircraft Oxygen Generation, AOG, Backup Oxygen System, BOS, Breathing Regulator 
Anti-G Valve, BRAG, Emergency Oxygen System, EOS, Environmental Control System, 
ECS, F-22, F-35, Human Systems Integration, HSI, Hypoxia, Life Support System, Life 
Sustainment System, LSS, Molecular Characterization, Molecular Sieve, On-Board 
Oxygen Generation System, OBOGS, Plenum, Pressure Swing Absorption, PSA, Zeolite 


15. NUMBER OF PAGES 

260 


16. PRICE CODE 


17. SECURITY CLASSIFICATION OF 18. SECURITY CLASSIFICATION OF 19. SECURITY CLASSIFICATION OF 
REPORT THIS PAGE ABSTRACT 

Unclassified Unclassified Unclassified 


20. LIMITATION OF ABSTRACT 

Public Release 



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